Katie Holmes @ Hairspray Premiere

Katie Holmes (in Alaïa) makes a surprise appearance, walking the red carpet in a little black mini at the New York premiere of Hairspray on Monday at the Ziegfeld Theatre.

Katie, 28, showed up to support the entire Hairspray cast, including fellow Scientologist John Travolta, who plays female impersonator Edna Turnblad in the film (the hefty mother of main character Tracy).

More pictures inside of Holmes not able to stop the beat…