"Heroes" cheerleader Hayden Panettiere was mistaken for Lindsay Lohan last night -- and was she ever pissed!

TMZ spotted Hayden leaving Hollywood hotspot L Scorpion last night with co-stars Milo Ventimiglia and Leonard Roberts, when a confused onlooker shouted out, "Give 'em hell Lindsay!" When one of the paps reiterated the fan's mistake, a huffy Hayden yelled back, "Don't ever call me that again!"

Somehow, the Lilo fan didn't hear Hayden clearly and called her Lindsay again! Before Hayden could fire up her vocal chords to respond a second time, a paparazzo screamed a string of choice obscenities to the confused Lilo fan.