We don’t see any newly introduced races in the remainder of the first revived season after Dalek, but for the record, the relevant stories are:
- The Long Game – The “monster” here is the Jagrafass, which is, so far as we can tell, a unique being, not a race.
- Father’s Day – The Reapers are said to be completely impervious to damage, which makes them more of an obstacle than something that can be described with creature statistics so I will, at least for the moment, pass on them.
- The Empty Child – The real threat here are the nanites that create the empty children and they are only doing what they are doing because of a very specific malfunction. Thus, the empty children themselves are a one-off thing and the malfunctioning nanites are (game mechanically speaking) a disease, not a monster.
- Boom Town – features the Slitheen.
- Bad Wolf – features the Daleks.
Although we do briefly see a dead Wirrn in a later story, they otherwise do not appear again in the TV show. They do, however, feature in the 1998 novel Placebo Effect and in four audio stories. The most notable of the latter are perhaps Wirrn Isle, a direct sequel to The Ark in Space, and Wirrn Dawn, which is essentially Aliens with Wirrn instead of xenomorphs. As usual, a few comics and short stories round out the total.
Description and Biology
When it comes to some of the more non-humanoid aliens in the classic TV series, it can often be difficult to determine how much of their appearance is how they are ‘supposed’ to look and how much is down to the limitations of special effects, budget, and the need to fit actors inside the costumes. The Wirrn are an example of this, but by no means the most extreme, so we can make a reasonable guess at the intent.
Wirrn, then, physically appear much like giant insects, with some features resembling those of mantises and grasshoppers and others with less obvious analogues. Their general body form is insectoid, with a distinct head, thorax, and segmented abdomen. The thorax bears six legs, at least four of which are likely supposed to be carrying the weight of the body (they don’t on the prop used in the show, because the actors’ legs are inside the abdomen) and the front two of which can be used as arms. They don’t seem to have much in the way of hands on the ends of these limbs and, unlike many real-world insects, they don’t have wings.
The head has a pair of large eyes, which may or may not be compound, and a pair of long antennae. The latter are primarily used for the sense of smell in real-world insects, but they have other functions, too, so they may or may not be the same here. There are a pair of curved mandibles, but none of the other mouthparts a real-world insect would have, nor any ocelli. There is also a slender, antenna-like structure projecting from the forward part of the head which is presumably sensory in function.
Since they are aliens, and not real insects, we can’t make too many inferences about their internal anatomy. Nonetheless, their ability to move about without difficulty when they are as large as they are would imply the presence of an internal skeleton in addition to the chitinous plates on the outside of the body. A respiratory system based on tracheae wouldn’t work at that size, so they must have lungs of some kind – although not necessarily where we would expect them to be.
There are two stand-out features of Wirrn biology. The first is that they can survive without food, water, and even air for extended periods. Some real-world creatures, most famously tardigrades, can do much the same, entering a state of almost total hibernation until woken up by the presence of liquid water. In the case of Wirrn, however, they can remain active for at least some of this time, being able to survive in a vacuum because of an ability to convert their expired carbon dioxide back into oxygen. In reality, that would require an input of energy from somewhere else – possibly sunlight – but this isn’t specified.
The second feature, of course, concerns their life cycle. The Wirrn are eusocial insects, like ants or bees, with only a small number of reproductive females. The status of the males is unclear; it could be that all the other Wirrn are male and that only a minority get the chance to mate, but it’s also possible, that, like real-world eusocial insects, the majority of Wirrn are sterile and it’s not obvious which ones are the fertile males. It’s also possible, if less likely, that queens are parthenogenetic, and there are no fertile males at all.
The queen lays her eggs inside warm-blooded vertebrates where they incubate until they hatch. Like bees and many other insects – but unlike the grasshoppers and mantises they otherwise resemble – Wirrn are holometabolous. That is to say, the egg hatches into a distinct larval form that later pupates to turn into an adult. The larva is a segmented worm-like creature with six short stubby limbs like those on the hind part of a caterpillar. They lack any obvious sense organs, and the mouth is simply a round opening without any mandibles or other visible mouthparts.
Where it gets weird is that the larvae secrete a slime that slowly transforms humans (and presumably similar vertebrates) into further larvae. Like regular larvae, these gain racial memory from their biological parent(s) and are also able to access the memories of the mammalian host. Since the host is apparently a kind of cow-like animal on their home planet, it’s hard to see what purpose this evolved for, but it’s certainly handy when the host happens to be a human whose world you wish to conquer.
There is a question as to just how humanoid the host has to be. Since they originally evolved to infect bovine creatures on another planet, the requirement is probably broad, and any warm-blooded mammal of sufficient size will do. So cats are likely safe because they are too small to form a proper larva let alone incubate an egg, but large dogs, cattle, horses, lions and so on are probably all fair game. Maybe ostriches, too, since they are warm-blooded and likely no more alien to the Wirrn than we are, but whether reptiles such as crocodiles – or Silurians – would fit the bill is less obvious.
Game Attributes
Despite the spindly appearance of their limbs, the Wirrn are no weaker than humans. They move slowly and clumsily but the latter may be more a factor of the costume’s limitations than something intended to be true of the race. Their armoured carapace is resistant to physical attacks, including blaster weapons, and their ability to survive for long periods in harsh environments implies a high degree of physical endurance. They are vulnerable to electricity, and likely to some other non-kinetic attack forms, too.
While they appear monstrous, the Wirrn are an intelligent species, on a par with humans and able and willing to communicate with them under the right circumstances. They don’t have any native technology that we know of, which limits the skills they will inherently possess, but their ability to absorb the knowledge of their host significantly offsets this. Nonetheless, the version I will provide stats for is one that has incubated in a non-sentient animal; additional skills can be added as required when other circumstances apply. The mandibles would be able to deliver a nasty bite, but the main threat in hand-to-hand combat would actually be how hard they are to injure, leading them to win a war of attrition.
There is also the matter of the other two instars – the larvae and pupae. The larvae are undeniably slow-moving and clumsy, even if the adults are not, and they lack any manipulatory appendages or natural weapons. Their hide is thick and resilient and can be easily regenerated, making them difficult to hurt, although not as much so as the adults. At this stage, they’re probably not fully sentient unless they have incubated inside or taken over a creature that already was and they’re apparently unable to communicate when in full larval form.
The pupae are immobile and harmless so, while they too are likely difficult to injure, they can’t fight back and so do not require creature statistics.
Special Abilities
The ability of Wirrn to survive in a vacuum is easily dealt with. Most systems will either provide a specific ability that covers this or would just have it be something that the creature “does” and that does not require a special description.
The transforming slime from the larvae is a more complicated issue. There is almost certainly a ‘saving throw’ (or equivalent) involved here; it’s just that the only person we see affected in the TV show happened to fail his. Once infected, however, while further saving throws – probably based on willpower – can slow down the rate of transformation, so far as we know, it is ultimately irreversible. So what we have is a slow-acting contact poison, but one that transforms the victim rather than killing them and, moreover, leaves them active while it is doing so.
One way to simulate this might be to reduce the victim’s dexterity or equivalent attribute since their ability to move about and manipulate objects is being steadily eroded as the transformation into a slow-moving slug-caterpillar continues. At a certain point, the transformation is complete and any skills that rely more on knowledge than physical ability or humanoid shape are carried over to the newly created Wirrn.
5E - Wirrn
Large monstrosity, lawful evil
Armour Class: 15 (natural)
Hit Points: 38 (4d10+16)
Speed: 30 ft.
STR 10 (+0) | DEX 10 (+0) | CON 18 (+4) |
INT 10 (+0) | WIS 12 (+1) | CHA 8 (-1) |
Saving Throws: Constitution +6, Wisdom +3
Skills: Athletics +3
Damage Resistances: Bludgeoning, Fire, Radiant, Slashing, Piercing
Senses: Passive Perception 11
Bite. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 6 (2d4+1) piercing damage.
Metabolic Resilience: The Wirrn can survive without food or water for ten times longer than a human. The Wirrn can hold its breath, and survive in a vacuum if necessary, for up to five days without ill effect. For each day thereafter, it takes a level of exhaustion.
Racial Memory: In addition to possessing the past knowledge of their parents, a Wirrn also has Proficiency in History, Medicine, Nature, Religion, Science, or Technology if its original host had Proficiency in those skills.
Challenge: 1 (200 XP)
5E - Wirrn Larva
Medium monstrosity, lawful evil
Armour Class: 12 (natural)
Hit Points: 30 (4d8+12)
Speed: 10 ft.
STR 10 (+0) | DEX 4 (-3) | CON 16 (+3) |
INT 8 (-1) | WIS 10 (+0) | CHA 6 (-2) |
Saving Throws: Constitution +5, Wisdom +2
Skills: Athletics +3
Damage Resistances: Fire, Radiant, Slashing, Piercing
Senses: Passive Perception 10
Slam. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 4 (1d6) piercing damage.
Infection: The Wirrn larva secretes an infectious toxin. If this touches the bare skin of a warm-blooded vertebrate-like creature, the creature must make a DC 10 Constitution saving throw or become infected. Once infected, they begin to transform into a Wirrn larva. Each hour, they must make a DC 10 Wisdom saving throw or transform further, losing 2 points of Dexterity in the process. Once they have lost 8 points of Dexterity in this way, they are fully transformed and replace their original statistics with those of a Wirrn larva.
Pupate: When a Wirrn larva pupates, it is considered to suffer the Paralysed condition until it emerges as an adult. Its statistics otherwise remain unchanged.
Challenge: ½ (100 XP)
BRP - Wirrn
STR 3D6 (10-11) | CON 2D6+12 (19) | SIZ 2D6+9 (16) |
INT 2D6+6 (13) | POW 3D6 (10-11) | |
DEX 3D6 (10-11) | CHA 2D6 (7) | |
Hit Points: 18 | Move: 10 | |
Base SR: 4 | Damage Bonus: +1D4 |
Armour: 6-point chitinous exoskeleton (no effect against electrical attacks)
Skills: Climb 50%
Combat Skills: Bite 50% (1D6+1D4 damage)
Metabolic Resilience: The Wirrn can survive without food or water for ten times longer than a human. The Wirrn can hold its breath, and survive in a vacuum if necessary, for up to five days without ill effect. Each day thereafter, it takes 1D6 damage that cannot be healed without returning to a breathable atmosphere.
Racial Memory: In addition to possessing the past knowledge of their parents, a Wirrn also retains any of the following skills its host body possessed: Artillery, Craft, Drive, Heavy Machine, Knowledge, Language, Literacy, Medicine, Navigate, Pilot, Repair, Science, Strategy, Technical, Track.
BRP - Wirrn Larva
STR 3D6 (10-11) | CON 2D6+9 (16) | SIZ 2D6+6 (13) |
INT 2D6+6 (13) | POW 3D6 (10-11) | |
DEX 1D6 (3-4) | CHA 2D6 (7) | |
Hit Points: 15 | Move: 3 | |
Base SR: 7 | Damage Bonus: 0 |
Armour: 2-point bubbly hide
Combat Skills: Brawl 40% (1D3 damage)
Infection: The Wirrn larva secretes an infectious toxin. If this touches the bare skin of a warm-blooded vertebrate-like creature, the creature must make a CON roll against a resistance of 10 or become infected. Once infected, they begin to transform into a Wirrn larva. Each hour, they must make a POW roll against a resistance of 10 or transform further, losing 2 points of DEX in the process. Once they have lost 8 points of DEX in this way, they are fully transformed and replace their original statistics with those of a Wirrn larva.
Pupate: When a Wirrn larva pupates, it becomes immobile, with a DEX and Move of 0. Its statistics otherwise remain unchanged.
GURPS - Wirrn
ST 10 | DX 10 | IQ 10 | HT 18 |
Speed: 7 | Move: 5 | ||
Size: +1 |
Advantages: Damage Resistance +5, Extra Legs (+2), Oxygen Storage (5 days), Racial Memory (active), Radiation Protection/2, Reduced Consumption-3, Vacuum Support, Innate Attack: Bite (1d-2)
Disadvantages: Obsession (propagate the race)
Skills: Brawling-12, Climbing-12, Free Fall-12, Stealth-10, (other IQ-based skills possessed by the original host body)
GURPS - Wirrn Larva
ST 10 | DX 4 | IQ 10 | HT 18 |
Speed: 5.5 | Move: 2 | ||
Size: +0 |
Advantages: Damage Resistance +2, Dominance
Disadvantages: Mute, No Legs (slithers, larva only), No Manipulators, Sessile (pupa only)
Skills: Brawling-6
Savage Worlds - Wirrn
Agility: d6 | Smarts: d6 | Spirit: d8 |
Strength: d6 | Vigour: d12 |
Skills: Athletics d6, Fighting d6
Metabolic Resilience: The Wirrn can survive without food or water for ten times longer than a human. The Wirrn can hold its breath, and survive in vacuum if necessary, for up to five days without ill effect. Each day thereafter, they take a level of Fatigue.
Racial Memory: In addition to possessing the past knowledge of their parents, a Wirrn also retains any of the Smarts skills its host body possessed.
Pace: 6 Parry: 5 Toughness: 12 (3) Size: 1
Savage Worlds - Wirrn Larva
Agility: d4 | Smarts: d6 | Spirit: d8 |
Strength: d6 | Vigour: d10 |
Hindrances: Mute
Infection: The Wirrn larva secretes an infectious toxin. If this touches the bare skin of a warm-blooded vertebrate-like creature, the creature must make a Vigour roll or become infected. Once infected, they begin to transform into a Wirrn larva. Each hour, they must make a Spirit roll or transform further. After four failed Spirit rolls, they are fully transformed and replace their original statistics with those of a Wirrn larva.
Pupate: When a Wirrn larva pupates, it becomes immobile, with an Agility and Pace of 0. Its statistics otherwise remain unchanged.
Pace: 2 Parry: 2 Toughness: 8 (1) Size: 0
STA - Wirrn
Control: 8 | Fitness: 10 | Presence: 8 |
Daring: 9 | Insight: 8 | Reason: 8 |
Command: 0 | Security: 2 | Science: 0 |
Conn: 0 | Engineering: 0 | Medicine: 0 |
Stress: 12 | Resistance: 2 |
Traits: Immune to Vacuum
Metabolic Resilience: The Wirrn can survive without food or water for ten times longer than a human.
Racial Memory: In addition to possessing the past knowledge of their parents, a Wirrn also retains any Science, Conn, Engineering, or Medicine skills its host body possessed.
STA - Wirrn Larva
Control: 6 | Fitness: 9 | Presence: 8 |
Daring: 9 | Insight: 8 | Reason: 8 |
Command: 0 | Security: 0 | Science: 0 |
Conn: 0 | Engineering: 0 | Medicine: 0 |
Stress: 9 | Resistance: 0 |
Infection: The Wirrn larva secretes an infectious toxin. If this touches the bare skin of a warm-blooded vertebrate-like creature, the creature must make a Fitness + Security roll against a difficulty of 3 or become infected. Once infected, they begin to transform into a Wirrn larva. Each hour, they must make a Daring + Command roll against the same difficulty or transform further, losing a point of Control in the process. After four failed rolls, they are fully transformed and replace their original statistics with those of a Wirrn larva.
Pupate: When a Wirrn larva pupates, it becomes immobile, unable to perform any active tasks or oppose any attacks. Its statistics otherwise remain unchanged.
