Mine are going to be a little different since I've only been following football for the past 6-7 years so I can't just say the obvious ones other people are saying when I didn't actually grow up with them. But I thought I would post mine so you guys can get an opinion of a young American who didn't grow up on the sport.
1. Steven Gerrard - yes yes I'm well aware I'll probably be laughed at here, but tbh he is the first footballer I ever admired and I'm going to admit that. Liverpool were the first club I knew and he became their captain around the time I started following them. Watching him lead Liverpool to that 2005 CL title was something else, the way that game turned out left me absolutely speechless. While I'm definitely aware that he is well past his prime and has done some questionable things in his personal life, etc. he will always be important to me, since he was essentially the first favorite player I ever had.
2. Fernando Torres - obvious that I would put him here.
In short as soon as talks started that he would join Liverpool, me knowing little about him at the time did some research and watched a bunch of footage of him playing for Atletico Madrid and I was utterly impressed. Absolutely fell in love with the way he played. When he showed up for Liverpool my love for him got even greater, he has done great things for a Liverpool side that has severely dwindled in form as of late. Also, it was because of him that got me to watch the Spanish NT progress through the Euro 08 and take the title, something which made me very happy and helped introduce me to Spanish football (as I did not watch Barca yet at this time).
3. Xavi - the main force I noticed in Euro 08, yes Torres scored the winning goal, which made me ecstatic, but it was ultimately set up by Xavi and he did much more for the team throughout the tournament as well. I grew to admire him greatly and he is one of the reasons I began to take notice to Barca after Euro 08, took me a while since I had been so EPL-minded up to then (something I regret, I wish I had been more open-minded in the past. I missed out on so much, for ex. Ronaldinho and that part of Barca's history). But anyway, I regard him as one of the greatest, if not THE greatest, midfielder in the world and I'm proud to be a fan of his and put him in this list.
4. Lionel Messi - best player in the world since I started following football. Enough said, there is nothing I could say that could do him justice.