Familiars

Source: Monster Manual p. 347

Any spellcaster that can cast the find familiar spell (such as an apprentice, warlock, or wizard) is likely to have a familiar. The familiar can be one of the creatures described in the spell (see the “Player’s Handbook”) or some other Tiny monster, such as a crawling claw, an imp, a pseudodragon, or a quasit.

Note

This variant is intended for NPCs. (https://twitter.com/JeremyECrawford/status/920714594334654465)