Christo and Jeanne-Claude--Let's start with an easy one. Some people would argue that Christo jumped the shark as he emerged from his mother's womb, but the Pissy Populist One was quite good early in his game. It's hard to pinpoint the exact moment when this duo jumped the shark, but the Cheez-it promenade of The Gates certainly seals the deal.
Elizabeth Peyton--The official court painter of the boys from Oasis and of laconic pretty boys wearing expensive shirts jumped the shark at the precise moment that you realized Peyton uses the exact same red when painting everyone's lips.
Gregory Crewdson--Debate rages on when this hyper-cinematic Yalie photographer passed the point of no return. Was it when he created his unintentionally self-parodying set of photos for the New York Times in which he recast his David Lynch rip-off scenes with celebrities like Julianne Moore and William H. Macy? Or was it solidified at his current exhibition at Luhring Augustine Gallery in New York, where it became undeniably clear that instead of forging new ground or exploring fresh ideas, Crewdson has become obsessed with one-upping his production values at the expense of originality?
Andrea Fraser--I suppose it was inevitable, and not entirely indefensible. Fraser's 2004 untitled video showed her fucking an anonymous art collector who paid $20,000 for the "collaboration." Regardless of whether you think the piece was a provocative statement or a whorish self-promoting shock move (or a jack from Yoko Ono's 1964 Cut Piece), the problem is that there's nowhere for Fraser to go from here.
Portland Art--It is with a slight sense of failure that I don't have a Portland artist to include on this list. This certainly isn't for fear of having someone else cross me off their list of favorite people. Rather, in the three years that I've been observing the local art scene, no artist has made a singularly bone-headed move to eradicate any great prior accomplishments. (Certain, ahem, institutions are another story). I can't think of one artist who has forced me to reverse my position on their work. Readers, on the other hand, are encouraged to send in their thoughts on Portland artists who have jumped the shark to firstname.lastname@example.org.