Fleur:  flower in French
Hagrid:  hung over With Hagrid's drinking problem, it sure fits
Snape:  a town in England that J.K. has been to.
Dumbledore:  means bumblebee
Draco:  means dragon
Minerva McGonagal:  In Greek language it means Goddess of Wisdom
Lupin:  wolf like
Sirius Black:  means Dog Star
Argus Filch:  Filch means to steal in a nasty way. In Greek Mythology Argus was a monster a thousand eyes.
Ron Weasley:  Means "Running Weasel" in another language. It was also a man who was brilliant at chess and never lost a game (like Ron!). Look at this! : "Running Weasel" died one day when a rat had been dyed yellow by his soldiers for fun, and he knocked over a lamp in his palace, which burned to the ground - killing him!
Voldemort:  means flight of death
Gilderoy Lockheart:  Golden King
Flitwick:  a town in Britain
Crucio:  Latin word for torture
Ludo Bagman:  Latin for I play