Hayden Panettiere's Bikini ... Hello Kitty!!!

6/7/2010 5:03 AM PDT BY TMZ STAFF
She's dating a world-class boxer ... but Hayden Panettiere appears to be the one in peak physical condition.

Hard-bodied Hayden hit the beach in Malibu this weekend ... with what appears to be a Hello Kitty bikini and ... zero percent body fat.