I have two nominees, the first of whom is Margetson. My memory of him is that he occasionally displayed vague vestiges of competence, but when he was bad he was catastrophically so. The game against Everton on the last day of the 1992/93 season, when he had to be subbed for his own good at the break after being at fault for three goals and lucky to get away with other errors, was probably the worst goalkeeping display I've ever seen. It utterly defies belief that he then had five more seasons at the club, but the decision not to dispense with him eventually did come home to roost.
Margetson made two dreadful errors to cost us points in the relegation run-in when we went down to the third tier in 1998. One was the Easter game at Wolves where the home team levelled late on after Margetson kept them in the game with, if I recall correctly, a corner he dropped into his own net under no real pressure. The other, little remembered thanks to Jamie Pollock's amazing own goal in the same match, was against QPR in the final home fixture; he allowed them to equalise Kinkladze's early strike by idiotically picking up a backpass, then immediately handing over the ball so they could score from a quick free kick. They were two disastrous and abysmal pieces of goalkeeping within five games at such a crucial time for the club. If we'd had a competent back-up 'keeper at that time, I'm convinced we'd have survived.
The other one that strikes me as worth a mention is Kevin Stuhr Ellegaard. He had a career in the game so must have improved, but he was dreadful when, as a young player, he first made our team. In the old days, before goalkeeper subs, you occasionally used to see an injured goalkeeper replaced by an outfield player, and the whole rest of the team usually used to drop back, defending desperately in depth to protect the novice custodian. Ellegaard with us circa 2004 is the only specialist goalkeeper whom I can recall ever making his teammates adopt the same approach.
www.premierleague.com
www.footballdatabase.eu