The upcoming project will center on a husband and wife, Ben (McDermott) and Vivien Harmon (Britton), who move to a haunted San Francisco home in hopes of rebuilding their marriage after a miscarriage and an affair.
Lange will play Constance, the couple's nosy next-door neighbor who holds information about their new residence. O'Hare is set to play Larry the Burn Guy, a former resident of the home.
McDermott appeared Off-Broadway in The Treatment and is best known for his work on the television legal drama "The Practice." Lange was seen on Broadway in The Glass Menagerie and A Streetcar Named Desire, and O'Hare's credits include Elling, Take Me Out, Inherit the Wind, Sweet Charity, Assassins, Major Barbara and Cabaret.
"American Horror Story," to be directed by Murphy, will begin shooting after Murphy and Falchuk wrap production on "Glee." The pilot is set to launch on FX in the fall.
