Born: c. 1960 (CR, OP28 - same age as Snape); Lupin is a half-blood Wizard (one Muggle parent or grandparent) (WBD)
Middle name: John (WBD)
Hogwarts: Sept 1, 1971 - 1978, Gryffindor House (WBD)
Nickname: Moony (PA17), because of his lycanthropy
Eyes:
Hair: light brown, prematurely gray (PA5), gets a bit hairier than normal once a month
Build:
Distinguishing features: suffers from lycanthropy (i.e.: he's a werewolf); consequently often looks ill and exhausted, and is usually very shabbily dressed since it's hard for him to find paid work (PA5, 18; OP3)
Voice: hoarse (PA5)
Field: Defence Against the Dark Arts teacher (on Hogwarts staff 1993 - 1994)
Unusual abilities: together with Wormtail and the Weasley twins, probably knows the castle and grounds of Hogwarts better than anyone living (PA18)
House: Gryffindor (OP9, OP30, WBD - same House as James Potter)