Derrick Vann is a corrupt and brutal cop in the 2005 hit movie The Man.
He was portrayed by Samuel L Jackson.
He is a villain because of what he does. He takes a man, Andy Fidler, without a warrant, and literally kidnaps him and coerces him into cooperating as a suspect. In all fairness, however, it's mostly because Andy was caught with a gun (which is illegal to own without a license in Detroit, the movie's setting). However, even after Fidler tells him the truth, he is coerced into this activity against his will. He doesn't even inform Fidler of his rights, he just sadistically takes him against his will.
He does many other nasty things in the process. He makes threats of violence against our protagonist, even sadistically claiming he'll put a bullet in "part of your ass you really need." He even threatens to hit Fidler with a book when Fidler realistically claims that Booty can't give a name. This is not a cop you wanna be around. Because Fidler's talking gets on his nerves so much he throws him and locks him in his trunk.