a teaching/research 'fellow' [=a graduate student who gets money in exchange for teaching/research]
He attended the concert with a 'fellow' student. [=someone who is a student, as he is]
He has always tried to be of service to 'his fellow man'. [=to other people]
(..) What's this? Looks like old Shelob's been having a bit of fun. Killed another one, has she? No. This fellow ain't dead. Not dead? She jabs him with her stinger, and he goes as limp as a boned fish. Then she has her way with them. That's how she likes to feed. (..)2003 The Lord of the Rings: The Return of the King