It may also be worth noting that the alien race the Foamasi, from the Fourth Doctor TV story The Leisure Hive, are essentially the same concept as the Slitheen, although they look quite different out of their skin suits and lack the biological peculiarities. They’ve proved less popular, only re-appearing in one of the ‘90s novels.
Description and Biology
The Slitheen are, of course, an organised crime family, not an alien race per se. The species they belong to are called the Raxacoricofallapatorians, which rather explains why the family name gets used more often. The Raxacoricofallapatorians are large hairless humanoids with long claws, large eyes, and arms much longer in proportion to their bodies than is true of humans.
Despite their roughly humanoid form, Raxacoricofallapatorians are biologically quite different from humans and, in many respects even from, say, Silurians or Sontarans. They are said to be largely made of “calcium phosphate”. This is a rather vague term, referring to a number of different chemicals – one of which, hydroxyapatite, is the primary mineral component of human bone and tooth enamel. It’s not at all obvious how an apparently organic being could be made out of what is essentially a mineral salt and still less why they would react explosively with vinegar if they were (calcium phosphates do dissolve in acetic acid if left for long enough, but you may have noticed that your teeth do not explode when you eat a pickled onion). But we’ll let that pass.
The large, dark eyes would imply strong night vision, although an official webcast suggested that they were for vision in blizzard conditions rather than a product of a nocturnal lifestyle (not that I'm sure why that would work). They are also said to have a remarkably keen sense of smell.
Since they don’t wear clothing when out of their skin suits, we can also make some speculations about their biology. For instance, males and females look much the same, so it seems unlikely that they are mammalian. They also appear to lack any external genitalia. One possibility here is that they use external fertilisation in a pool of water, as some amphibians do, but another is that the male’s intromittent organ is retracted into a protective pouch when not in use. We know that they lay eggs although it’s interesting that they also possess what looks like a navel. Although it’s not impossible, depending on the structure of the egg, this is not what we’d expect in an oviparous animal – but it could be that it is an orifice of some kind and not a navel at all.
Game Attributes
Given their greater-than-human size and disproportionately long and muscular arms, we can safely say that Raxaocoricofallapatorians are significantly stronger than humans – likely even an “average” member of the species would be around the maximum unmodified human strength. They are also physically resilient, although perhaps not exceptionally so for their size. The long claws on their fingers make it unlikely that they are highly dextrous when it comes to fine manipulation, but they move quickly and are more agile than they might appear. Presumably, their mental attributes are similar to those of humans since there seems little to indicate otherwise.
For our purposes, the typical member of the race we’re going to stat out here is a low-ranking member of the Slitheen family. Doubtless, this is not typical of Raxacoricofallapatorians as a whole, since they must have numerous shopkeepers, accountants, mechanics, and all the various other jobs that keep an advanced civilisation ticking over but it’s the Slitheen we’re primarily interested in here, and they (or some of their close relatives) are likely to be how the race is most often encountered.
Taking that approach then, we’re looking at somebody who is basically a low-level scavenger/hoodlum. Their combat skills are likely to be reasonable, although we don’t really see them using guns (difficult with their hands, perhaps) so it’s most likely hand-to-hand combat, albeit aided by claws that are basically swords. Their other skills will be based on intimidation, dealing with the criminal underworld, and technology with a particular emphasis on anything that lets them get past security. Despite this “rogue”-like part of their skill set they don’t seem especially stealthy and they certainly aren’t going to be able to pick pockets in their regular form. Given their modus operandi, we can also say that they must have good social and acting skills to fool members of other species into thinking they are something they are not.
Special Abilities
In addition to their purely physical traits, the Slitheen are notable for a couple of particularly useful features. Firstly, there’s the ability to disguise themselves as humans. This uses advanced technology, rather than anything innately biological, but it’s notable that, while inside the skin suit, they can move no faster than regular humans and we’d expect their strength to scale down accordingly as well. There’s no real reason to suppose that their statistics would otherwise change, however.
The second feature is that females of the species can create poison darts in their fingers that they can fire at threats. From what we see, these don’t have an especially long range and would be best used close-up. We don’t know how effective the poison is, but there seems little point in it if it isn’t at least debilitating to a human-sized target, perhaps similar to snake venom.
5E - Slitheen
Large humanoid, neutral evil
Armour Class: 12 (natural)
Hit Points: 45 (6d10+12)
Speed: 40 ft.
STR 18 (+4) | DEX 12 (+1) | CON 14 (+2) |
INT 10 (+0) | WIS 10 (+0) | CHA 12 (+1) |
Skills: Deception +2, Intimidation +2
Damage Vulnerabilties: acid
Senses: Passive Perception 10
Actions:
Claws. Melee
Weapon Attack: +3 to hit, reach 10 ft., one target. Hit: 9 (1d8 +4)
slashing damage.
Dart
(females only, once per long rest). Ranged Weapon Attack: +3 to
hit, range 20/60 ft., one target. Hit: 1 piercing damage, and the target must
make a DC15 Constitution saving throw, taking 7 (2d6) poison damage on a failed
save, or half as much damage on a successful save.
Challenge: 1/2 (100 XP)
BRP - Slitheen
STR 2D6+12 (19) | CON 2D6+6 (13) | SIZ 2D6+12 (19) |
INT 2D6+6 (13) | POW 3D6 (10-11) | |
DEX 2D6+6 (13) | CHA 3D6 (10-11) | |
Hit Points: 16 | Move: 15 | |
Base SR: 4 | Damage Bonus: +1D6 |
Armour: 1-point leathery hide
Skills: Appraise 40%, Disguise 80%, Fast Talk 40%,
Jump 40%, Repair 40%
Combat Skills: Brawling 60%, damage: 1D8+1D6
Dart (females only): Missile weapon attack,
range 10, 1 point damage plus POT 10 poison.
GURPS - Slitheen
ST 18 | DX 12 | IQ 10 | HT 12 |
Thrust: 1d+2 | Swing: 3d | ||
Speed: 6 | Move: 8 | ||
Size: 1 |
Advantages: Alternate Form, Alternate Identity, Claws
(Long Talons), Damage Resistance 1, Discriminatory Smell, Innate Attack 2
(females only, toxic, reduced range/2, resistible)
Disadvantages: Enemies (rivals), Greed, Reputation
(criminal), Vulnerability (acid)
Skills: Acting-14, Brawling-14, Computer
Operations/TL10-11, Electronic Operations-10, Fast Talk-12, Innate Attack-13,
Intimidation-13, Streetwise-11
Savage Worlds - Slitheen
Agility: d10 | Smarts: d8 | Spirit: d8 |
Strength: d12 | Vigour: d10 |
Skills: Electronics d4, Fighting d6, Intimidation d6
Edges: Fleet Footed, Streetwise
Hindrances: Wanted (minor)
Powers (females only): Bolt
Special Abilities: Claws, Environmental Weakness
(acid)
Pace: 8 Parry: 5 Toughness: 9 Size: 2
STA - Slitheen
Control: 8 | Fitness: 12 | Presence: 9 |
Daring: 9 | Insight: 8 | Reason: 8 |
Command: 0 | Security: 2 | Science: 1 |
Conn: 0 | Engineering: 1 | Medicine: 0 |
Stress: 14 | Resistance: 0 |
Claws: Melee, 2^, Vicious 1
Dart (females only): Ranged, 1^, Deadly