Filius Flitwick is the Charms Professor at Hogwarts School of Witchcraft and Wizardry. He is a short man and a very intelligent one as well. He taught Harry Potter, Hermione Granger, Ron Weasley and many others.
He helped set up many defense around Hogwarts school and was in charge of many security logistics the school might encounter. He was extremely gifted in Charms, his teaching position, and could perform difficult spells with ease. He also assisted in the removal of Severus Snape from Headmaster position at Hogwarts. He was also the Ravenclaw House chair.
In the films, he has had two drastically different styles. The leading picture here is his appearance from Goblet of Fire
onward, while the photo to the left shows his older look from the first two movies.