I... have no idea what StarChan answered to, but vampires done well in games are awesome to play... and extremely rare.
On to the OP's question:
Paladin - Seems quite clear to me, holy warrior, mix between fighter and cleric but while clerics can also be evil, or plain neutral, paladins are always good. Tanks, tough and strong, but speed is not their forte, heaviest armor and shields, good with weapons too but they excel more at defense, both their own and that of their companions. Magical abilities can follow the same pattern, protection and healing first, offensive abilities perhaps focused on their typical enemies, such as undead, demons and evil-aligned characters if alignment is used. In terms of social skills, can be wise to some extent but their rigidity and holier-than-thou attitude can bother many, but they can lead groups quite well.
Ranger - Nature fighter, with many skills related to living in the wild and dealing with animals, including having them as companions and training them. Agile, quite fast, moderately strong and tough. Stealthy, skilled with traps, though mainly an expert at these in the wild, may also have some other thieving skills to a moderate extent. Lightly armored, focused on offense, primarily archer but also skilled with some thrown and some one-handed, mainly bladed, melee weapons. Can use what nature provides to create what's needed to cure or boost abilities, maybe poison as well. In terms of magic, nature-based if it exists, but limited, and could accept non-magic rangers as long as they'd be able to gather natural ingredients easily and create mixtures, potions and so on from them. Not one for cities or human company in general for that matter, so social skills are lacking, but nevertheless can be good group leaders. In terms of alignment, can be anything really.
Druid - Nature's guardian, aided by natural magic. Approaching the ranger in wilderness- and animal-related skills, though they may be a mix of knowledge and magic, and likely more focused on survival and peace. Not much for physical combat and not ranking highly in the related attributes, but can be somewhat stealthy when needed, especially in wilderness areas. Limited, possibly very limited, weapon and armor skills. Magic and crafting skills strictly tied to nature, but can become truly powerful, for both offensive and defensive uses. Wise in their ways but also not one for cities or human company, social skills are lacking and don't tend to be suitable to lead groups. In terms of alignment, typically they say druids are neutral, but I'd also see them as potentially good. Can't see evil druids though.
Ninja - Master assassin. Extremely fast and agile, pretty strong, moderately tough. Masterful with thrown weapons and exotic, mainly light, melee weapons, also skilled with crossbows. Highly focused on offense, usually at most lightly armored, relying on not getting hit in the first place. Masters of stealth and all thieving skills, like traps, poisons or locks. Also masters of dirty fighting, knowing all sorts of tricks to quickly eliminate or incapacitate a target. Can use any magical items they can get their hands on, but don't usually have magic abilities of their own. Tend to work alone or, if groups are needed, not care to have anything else to do with their companions once the job's done. In terms of alignment, have some difficulty in seeing good ninjas, but that may only apply to a paladin's sense of good, so can have rather... Machiavellian good ninjas.
I'll leave the samurai for later, not a class I recall ever dealing with really, and less clear on how I'd see it properly implemented. Roughly, fighter-ninja in a way, but with high social skills too, but that may not explain it too well.
Post edited May 17, 2019 by Cavalary