Before he began breaking tween hearts everywhere as High School Musical's Troy Bolton, Zac Efron appeared in a 2003 episode of ER as Bobby Neville, a shooting victim who didn't make it out of County General alive. Meanwhile, a year into her Sonny with a Chance run on Disney Channel, Demi Lovato arrived in a 2010 Grey's episode to show fans that she could handle material darker than anything the Mouse House would ever let air. She played Hayley May, a young diasnosed paranoid schizophrenic who had tried to claw her eyes out.