Sandorst in The Autumnlands: Tooth & Claw who sinks so low as to blow up a bridge carrying the soldier protecting him to steal the glory for himself.
Elixir from X-Men. He subconsciously used his powers to change his skin into a reflective golden color so he'd stand out more. Before he discovered he was a mutant, he joined an anti-mutant terrorist group because he thought it would make him more popular.
Also, the Mimic, from earlier in the X-Men. This is about 90% of his motivation for screwing around with the X-Men, showing off.
Emma Frost. She wears those Stripperific suits on purpose. (Although it's also partially for psychological warfare against men, as she has claimed.)
One of the reasons why The Riddler from Batman does what he does.
Booster Gold often ruins covert hero operations by alerting his publicist to where he and the rest of the Justice league will be just so he can draw a crowd.
Later subverted when Booster gets recruited by Rip Hunter as a guardian of the time stream. By this point Booster has become a competent, serious hero, but he has to maintain his public image as a screw-up attention whore to avoid getting killed in the crib.
Dreamkeepers has Mace, Whip and Namah, especially in Prelude.
"Musical sensation" and political advisor Tinsel might very well be the mistres of this trope. One scene has her walking through a very large room, with several bickering politicians a little to the side of her path. She detours right into the center of the crowd, only to lament that she's "busy", and walks off. And considering her usual wardrobe choices, the latter word in this phrase is decidedly appropriate.