(1) Steve Brookstein
The first winner of the X-Factor, he had some initial success as do all X-Factor winners. However, it was very temporary and he pretty much disappeared without a trace soon afterwards. There were reports that he fell out with the record company and that was part of the problem, although whether that is true or not is impossible to know without being on the inside!
(2) Shayne Ward
A much more popular winner than series one, it was thought that Shayne Ward would have enduring fame. He had a strong voice that could hit the high notes and certainly had initial success. However he soon disappeared too, although appears to be making a comeback again so it will be interesting to see if he manages to achieve anything with so many X-Factor winners out there now trying to earn a crust.
(3) Leona Lewis
The most famous and successful of all the X-Factor winners by quite some margin, particularly having impacted on the coveted US market and having done really well over there. Probably the only X-Factor winner whose success after the show and talent is unquestioned.
(4) Leon Jackson
The series four winner, and almost certainly the one that you've forgotten about right? Leon Jackson somehow managed to win although everyone thought that Rhydian Roberts was going to win the series. What happened after that? No-one knows, after the obligatory Christmas song he appears to have disappeared!
(5) Alexandra Burke
She has done quite well, having won series five, and having had quite a few fairly catchy songs and a few decent chart positions after the X-Factor, so like Leona it looks like she could be set to stay for a while yet, and certainly whilst she remains popular and her material keeps on selling.
(6) Joe McElderry
The winner of series six, and great things were expected of him, although he had to wait a week longer than most X-Factor contestants to get his first number one! Then disappeared and has recently made a comeback after performing on series seven of X-Factor, it will remain to be seen whether his new material has any impact now the instant shine of him having won the show has faded.