Imps & Quasits - Fiendish Familiars

Imps are a small, slightly build fiends that exist across many hellscapes in the afterlife. They are universally depicted as having bat like wings, small horns, a tail, and reddish skin. Many have a cackling laugh, and love to cause mischief & mayhem, despite following orders from superiors to the letter. They are physically weak, but have nasty bites & tempers to match.
Quasits are another small fiend, with strangely shaped humanoid bodies, and two elongated horns, large black eyes, green skin, and long dexterous tails. They have large pointed ears, and a mouth full of sharp teeth. Completely chaotic, unless monitored they will cause havoc in an area, and attack anything of their size or smaller.
Both these fiends are able to be summoned and used as familiars by spellcasters. Though saying that, only the most evil mage would consider having such a creature of either kind as a familiar.