Depending on which book you read, you will encounter different Defense Against the Dark Arts professors. In fact, no DADA professor has lasted beyond one book at Hogwart's. Below--listed by order of appeareance-are the Hogwart's DADA teachers who were employed during the first three years of Harry's attendance.
Argus Filch:
The Despised caretaker at Hogwarts. He was born a squib, meaning he was a non-magical person from a magical family. Bitter towards students and their spell-casting abilities, he-and his cat, Mrs, Norris-delight in catching and punishing students.
Rubeus Hagrid:
The Keeper of Keys and Grounds at Hogwarts. Currently teaches the Care of Magical Creatures. He was expelled his 3rd year, due to Tom Riddle. Harry Potter cleared his name in the second book by exposing the real story of the Chamber of Secrets. Hagrid loves odd and dangerous animals, particularly dragons and Blast-Ended Skrewts.
Madame Pomfrey:
The school nurse, a very capable witch. She can regrow bones and express her thoughts very well.
Professor Vector:
Teacher of Arithmancy
Quirrell:
This was the DADA professor during Harry's first year at Hogwarts. Professor Quirrell appeared a very weak and frightened man, but turned out to be in alliance with Voldemort himself. He wore a turbin to hide the fact that Voldemort was using his body as a host until his strength returned and, because of this, appeared as another face where the back of his head should have been.
Gilderoy Lockhart:
The second year of Harry's attendance at Hogwart's saw Gilderoy Lockhart as the DADA professor. Highly opinionated and widely known for his "achievements," Lockhart was rather fond of himself. He attempted to take Harry under his wing and entice him with fame and his shallow ways. In reality, Lockhart took credit for the achievements of other witches and wizards. The only thing he actually excelled at were memory charms-one of which proved to be his downfall.
Remus J. Lupin:
Professor Lupin attended to the DADA classes in Harry's third year of schooling. He is a worn man, who is tied in with Harry's father as well as Sirius Black, Peter Pettigrew, and Severus Snape. Remus J. Lupin was the best DADA teacher Hogwart's had seen since the start of the series, but when a terrible secret about him got "accidentally" revealed by Professor Snape, we again bid adieu to yet another Defense Against the Dark Arts professor.
Mad-Eye Moody: The DADA professor in Harry's fourth year. Carzy, paranoid, scared, and fitted with a magical eye that can see through anything, he is an Auror; one of those who sought out the dark wizards of Voldemort and saw to it they were destroyed. Moody appears to be Harry's friend in book IV, but there is something about him nobody discovers until the end....
Professor Sprout:
Professor of Herbaology at Hogwarts and the head of Hufflepuff. Exposes students to such things as Mandrakes, which are deadly if their cries fall upon human ears.
Professor Flitwick:
Teacher of Charms. Flitwick is so short that he stands upon a stack of books to reach his podium.
Madame Hooch:
Coordinator of Quidditch at Hogwarts. She also teaches broom-flight and tactics to first years.
Sybil Trelawney:
The Divination professor. Her predictions seldomly come true. Many of the students think her a mad old bat, especially the cool and logical Hermione Granger.