Hayden Panettiere is a Protective Sister

Heroes hottie Hayden Panettiere takes on the role of protective older sister as she protects brother Jansen, 13, on Thursday night in Los Angeles.

The brother-sister team attended the Halo 3 party at the Level 3 nightclub in Hollywood and then headed to former Saved By The Bell star Mario Lopez‘s birthday party.

Chaperone for the night? Mommy Lesley Vogel.

10+ pictures inside of Hayden and baby brother Jansen…