Filius Flitwick
Wikipedia
Harry Potter Character Guide
Filius Flitwick is the Charms Master at Hogwarts and the head of Ravenclaw house. He is a very short man. In Harry Potter and the Philosopher's Stone he uses his magical skills to help decorate the Great Hall for Christmas. He is also one of the teachers who cast spells to guard the Philosopher's Stone by putting charms on a hundred keys so they can fly, making it difficult to find the key to the door leading to the next chamber.
During Harry's second year, Flitwick helps Professor Sinistra carry a petrified Justin Finch-Fletchley to the hospital wing. He teaches the front doors to recognize a picture of Sirius after his second break-in in Harry Potter and the Prisoner of Azkaban, and to instantly lock down if he tries to break in. He helps patrol the perimeter of the maze for the third task of the Triwizard Tournament held in Harry's fourth year. He eventually removes most of the swamp that is created within the school by Fred and George in Harry Potter and the Order of the Phoenix, though he previously leaves the swamp untouched to annoy Umbridge. He does however, choose to leave a small patch of it behind, because he thinks it is a good bit of magic and a tribute to the Weasley twins. Near the end of Half-Blood Prince, Flitwick is sent by Professor McGonagall to ask Professor Snape to come to the aid of the Order of the Phoenix against the intruding Death Eaters. He collapses after requesting Snape's help at the battle.
In Harry Potter and the Deathly Hallows, Flitwick insists that Rowena Ravenclaw's Diadem is lost, and he is described by Harry as having been a model student who supposedly never entered the Room of Hidden Things, and so it never occurred to him that the diadem could be hidden there. Before the Battle of Hogwarts, Flitwick helps to chase Severus Snape out of the Hogwarts castle alongside professors McGonagall and Sprout, and to put protective charms around the castle to hinder Voldemort and his oncoming Death Eaters, and later fights the intruders in the battle, battling Corban Yaxley and later defeating Dolohov.
During Harry's second year, Flitwick helps Professor Sinistra carry a petrified Justin Finch-Fletchley to the hospital wing. He teaches the front doors to recognize a picture of Sirius after his second break-in in Harry Potter and the Prisoner of Azkaban, and to instantly lock down if he tries to break in. He helps patrol the perimeter of the maze for the third task of the Triwizard Tournament held in Harry's fourth year. He eventually removes most of the swamp that is created within the school by Fred and George in Harry Potter and the Order of the Phoenix, though he previously leaves the swamp untouched to annoy Umbridge. He does however, choose to leave a small patch of it behind, because he thinks it is a good bit of magic and a tribute to the Weasley twins. Near the end of Half-Blood Prince, Flitwick is sent by Professor McGonagall to ask Professor Snape to come to the aid of the Order of the Phoenix against the intruding Death Eaters. He collapses after requesting Snape's help at the battle.
In Harry Potter and the Deathly Hallows, Flitwick insists that Rowena Ravenclaw's Diadem is lost, and he is described by Harry as having been a model student who supposedly never entered the Room of Hidden Things, and so it never occurred to him that the diadem could be hidden there. Before the Battle of Hogwarts, Flitwick helps to chase Severus Snape out of the Hogwarts castle alongside professors McGonagall and Sprout, and to put protective charms around the castle to hinder Voldemort and his oncoming Death Eaters, and later fights the intruders in the battle, battling Corban Yaxley and later defeating Dolohov.