The close-up image appears to show Twisty the Clown Killer, a character who features in the upcoming season of the show, reported Entertainment Weekly.
'Freak Show' follows one of the last surviving freak show attractions in America in 1952, which is managed by Elsa Mars (Jessica Lange).
'White Collar' star Matt Bomer and Patti LaBelle are due to make an appearance, along with the world's smallest woman from India, Jyoti Amge.
The season also sees the return of Naomi Grossman's 'Asylum' character Pepper.
Show creator Ryan Murphy revealed that the season will show what happened to Pepper in the 12 years before she was sent to the asylum.