9. Samuel Eto'o
When you compare the impact a player had at both Madrid and Barcelona, few players can boast such polarising records as Cameroon legend, Samuel Eto'o.
Eto'o was barely used by Real in the early 2000s as he made just a handful of appearances before being farmed out on loan. He eventually signed a permanent deal with Real Mallorca, and it was on the tiny Spanish island he really made a name for himself.
The striker smashed in the goals and it wasn't long before the powers that be in Barcelona took notice, making their move to sign Eto'o in 2004.
It proved a wise move for the club and indeed, Eto'o, who found himself as the key striker in an exciting and trophy-laden spell for the Catalan club.
Eto'o forged thrilling strike forces with the likes of Ronaldinho and Thierry Henry, and while he had his problems with managers like Frank Rijkaard at times, there's little doubting his success at the club.
A goal in the Champions League final win over Arsenal only further cemented Eto's place in Barcelona folklore before he finally moved on to Inter Milan, again winning Europe's top prize, under Jose Mourinho.