The 50-year-old actor will portray a core villain on the fourth season of the series. Lynch is known for his role as Norm Gunderson in the movie Fargo, and Bud Morris on medical drama Body of Proof.
American Horror Story executive producer Tim Minear announced the casting at the program's San Diego Comic-Con debut over the weekend. He said Lynch's villain will rival Murder House's Rubber Man, Asylum's Bloody Face and Coven's Minotaur, and is guaranteed to "scare the [expletive] out of you."
Several cast members accompanied Minear to the event, and revealed their character names for the new season. Freak Show takes place in Jupiter, Fla. in 1950, and stars Jessica Lange as freak show manager and German expatriate Elsa Mars, Sarah Paulson as Siamese twins Bette and Dot Tattler, Michael Chiklis as strongman performer Wendell del Toredo, Angela Bassett as Wendell's wife Desiree Dupree, Kathy Bates as Wendell's ex-wife Ethel Darling, Evan Peters as Wendell and Ethel's son Jimmy Darling and Emma Roberts as Maggie. Frances Conroy, Gabourey Sidibe, Denis O'Hare, Jamie Brewer and Finn Wittrock also appear.
American Horror Story: Freak Show premieres in October, and Minear described the season as "Douglas Sirk meets Zodiac." Creator Ryan Murphy has said it has "a little bit more humor and a little bit more camp" than Asylum, but a darker tone than Coven.