Named Ashamed posted:

Jerry from Edward Albee's The Zoo Story is popular staple, but done to death.

Down the Road by Lee Blessing has several serial killer monologues.

Eric Bogosian is usually dark. His piece "Molecules" from one of his One Man shows, either "Pounding nails in the floor with my forehead" or "Sex, Drugs, Rock & Roll," is more gross than dark, but still dark.

Christopher Durang always does Black Comedy. Try "Man" from Laughing Wild. More angry at the world than evil though.

David Harrower's Blackbird is about a pedophile. Actually not that dark in an "evil" sense, but you might find something there.

LeRoi Jones' Dutchman has a monologue about how all we really need to do is kill somebody instead of letting out our aggression in art. The character is a 70's black man, so that might not work if you're not black.

Neil LaBute's "bash: the latter day plays" is all monologues. In one a young Mormon recounts his murder of a gay man. In another a Mormon father talks about secretly smothering his baby child when he thought he had lost his job and home.

Byron Lavery's Frozen is about a serial killer, but also has perspectives from the victim's family too.

David Mamet. Glengarry Glen Ross and Sexual Perversity in Chicago have some male monologues where the male speakers justify a perverse worldview. Those might be a stretch though. They're not really evil.

William Mastrosimone's Extremities has a rapist break into the home of 3 women. He does one monologue gloating about how he's going to rape them all. Probably more there too.

Martin McDonagh's The Pillowman has twisted poo poo the whole way through. Goldmine, but may be a little overdone at this point, especially for "dark" auditions.

Charles Mee's Bobrauschenbergamerica has a Mass Murderer Monologue from "Bob The Pizza Boy". He killed his family in a fit of rage, and tries logic to the audience why he should be forgiven.

Sam Shepard is often dark. Buried Child and The Curse of the Starving Class have men who are in complete despair about inheriting the failure of their fathers and America. Surreal too.

Michael Weller's Moonchildren has the Landlord of the characters' apartment burst in to tell them a twisted dream about ruling a village of African natives and impregnating the females with semen filled leaves.