Suppose I best answer my own question.
NFL: Larry Fitzgerald. The reason I'm a Cardinals fan, pretty much. I was mesmerised by his display in Super Bowl 43 and became a proper fan of the sport after that, he's a brilliant player and one of the nicest guys around. Going to be a very, very sad day when he hangs up his cleats. And I'm gutted he never won a ring because he absolutely deserves one.
F1: Mark Webber. Another gentleman, a largely under-rated driver and another who deserved a world title but agonisingly missed out. It should have been his in 2010 but alas, not to be. Plugged away for a long time in the midfield but proved when he had a competitive car that he had excellent ability and could give any of the biggest names a run for their money on his day.
Tennis: Andy Murray. Sorry, but it has to be. Following his career has been a mighty rollercoaster but he has given me some of the greatest moments in sport I could ever hope to see and that Wimbledon victory will live long, long in the memory. He's basically achieved everything there is to achieve in the sport and for a British player to do that, in an era competing against three of the best to ever play the game, is so impressive.
Football: James Coppinger. Over 600 games for Doncaster Rovers, key goals in almost all of our big successes over the past 15 years and once again, a complete gentleman. Class personified, he is irreplaceable and seemingly evergreen. The single greatest moment I've experienced as a sports fan to date was his last-ditch goal to win us the title at Brentford in 2013.