Power Girl's cleavage carrier almost qualifies as shirtless in itself. This spectatular Ordway image of two Power Girls forced me (forced me, I tell you) to examine the infamous Kryptonian Hooter Vent closely, because at first glance I thought we had a Knocker Knockout on our, er, hands.
The story that presents this incident could go either of two ways -- or, for that matter, both at once. It could be the long-overdue last time poor PG learns that Everything She Knows Is Wrong, culminating at last in a strong, clearly-defined character. Or it could be the DC equivalent of the Spider-Clone Saga.
[From Justice Society of America Annual #1.]