Winx Club is a phenomenon in Europe, and has even graced the USA twice: first, running from 2004-2009 (dubbed by 4Kids) and a second time, this time around, dubbed by Nickelodeon (2010-present.) While it still hasn't made quite the mark in America that it has in Europe, it's still a considerable success. However, before it became the smash-hit it is today, it went through several test stages, only fragments of which have been released.
Magic Bloom (1999)
The first known incarnation of the series was title Magic Bloom and was made circa 1999 as a proof of concept. In this stage, the main characters were aged 13-14 instead of 15-16, as they are in the series proper. There are rumors that the characters had different names, but there is no source for this information. Most notably, the series was, at this stage, made for a much younger audience in mind, and the character designs hadn't been finalized. The initial character designs and 20 seconds of footage have both been leaked onto the internet; the source of these are unknown.
Additionally, there are claims that 15 episodes were produced under this moniker and aired on Cartoon Network in 1999, and the episodes were later destroyed after it couldn't retain ratings, after which it was retooled into Winx Club. On top of being completely unsourced, there are no records of Magic Bloom appearing on Cartoon Network at any point in time, no one has come forward with recordings of the series, and funding 15 episodes of an animated series is expensive, so it's very unlikely that a then-small company, such as Rainbow sp.A, would fund an entire series run and then dump it because of bad ratings.
Winx: Just Fairies! (2001)
Even less is known about this stage of the series' development. One image exists with the Winx: Just Fairies! logo, which interestingly also has the finished designs of the three characters who appear in it. This was presumably the last stage that the show went through before becoming WInx Club.