Excellence in any kind of athletic endeavor will earn you endless recognition, numerous awards, and the chance to be immortalized in the hearts and minds of fans all over the world.

It may sometimes seem as though professional athletes get paid too much and become too famous, but when you see them perform at their peak, it’s hard not to come to the realization that you are watching someone truly special. At that point, you’ll probably be glad to pay extravagant ticket prices just for the entertainment of watching them continue to perform.

Sometimes, it even seems that pro athletes are so superior physically to the point where they can’t possibly go by the same laws of physics that average people do.

We’ve been fortunate enough to be introduced to some truly legendary sports figures this century, but there are some who manage to stand out even amongst the cream of the crop.

In this article, Jim Gray MD of Meridian, Mississippi highlights four American athletes who can stake a legitimate claim to being the Greatest of All-Time (GOAT) of their chosen sport. The list includes athletes from team and individual sports.

Just to be clear, the athletes below are being listed in alphabetical order and not in terms of how great they are compared to one another.

Let’s get started.

Tom Brady, American Football

It’s hard to imagine it now, but there was a point in time when Tom Brady was overlooked as a football player. Selected with the 199th overall pick in the 1999 NFL Draft out of Michigan, Brady was seen more as a third-string or even practice squad quarterback as opposed to someone who would start meaningful games in the league.

20 years later and Brady has established himself as one of the all-time greats, and many would even refer to him as the GOAT of the NFL.

Per Pro Football Reference, Brady has thrown for 70,514 yards over the course of his career and he’s also tallied 517 touchdown passes. That places him fourth and third all-time respectively in the aforementioned categories. He’s also a three-time league MVP (Most Valuable Player).

What separates Brady from his peers though are his accomplishments on the game’s biggest stage. The 41-year-old holds a 6-3 record in Super Bowl contests, and the three times that he and the New England Patriots lost were in close games.

Brady has often been the biggest difference-maker in the Super Bowls his team won as he’s taken home four Super Bowl MVPs.

LeBron James, Basketball

You don’t often see players with an almost endless amount of hype behind them live up to sky-high expectations, but LeBron James is one of the rare exceptions.

Ever since being drafted first overall by the Cleveland Cavaliers in 2003, James has done nothing but dominate on the basketball court.

James is already third all-time in terms of total points and he has a pretty good shot at overtaking Kareem Abdul-Jabbar before it’s all said and done. Even if James retired tomorrow, he would be the all-time scoring leader in the postseason, besting Michael Jordan by nearly 1,000 points, per NBA.com.

Unlike Brady, James does not have a bulletproof argument for being the greatest basketball player of all-time due in large part to his lackluster NBA Finals record (3-6), but with years still left to go on his career, he has a good shot at eventually earning that distinction by adding more accomplishments to his résumé.

Michael Phelps, Swimming

When you’re trying to think of the greatest Olympic performer of this century, there’s a very good chance that you’ll wind up naming Michael Phelps.

Phelps has taken home a total of 28 medals from the Olympics, including a mind-boggling 23 golds. The Baltimore, Maryland native peaked in 2008 at the Beijing Olympics when he won a total of eight gold medals while also setting seven world records, per Olympic.org.

Even as an elder statesman on 2016 U.S. Men’s Olympic Swimming Team, Phelps still managed to leave an incredible mark as he won an additional five gold medals.

Taking into account his other wins at events beyond the Olympics, Phelps has earned 66 gold medals. Phelps won’t be adding more to his impressive totals now that he’s retired, but even as they stand right now, his records will be difficult to break.

Serena Williams, Tennis

You can’t put together a list made up of the greatest American athletes of this century without naming Serena Williams.

Williams’ career actually dates back to the mid-90s when she made her pro debut as a teenager. She would net her first Grand Slam singles title in 1999 by defeating Kim Clijsters, but that was just a prelude of things to come.

In 2002, Williams would dominate the women’s tennis circuit, taking home the singles titles at the French Open, Wimbledon, and the U.S. Open. She missed out on winning all four Grand Slam titles since she had to withdraw from the Australian Open due to injury. Still, Williams managed to win four consecutive Grand Slam tournaments by winning the Australian Open in early 2003.

Her remarkable feat eventually became known as the “Serena Slam.”

For her career, Williams has amassed a 337-47 record in Grand Slam tourneys, according to the Women’s Tennis Association. She has come out on top of 23 Grand Slam competitions.

Williams has also won four Olympic gold medals. Three of those are doubles medals she earned while teaming up with her sister Venus.

There are so many other American athletes who could have made this list including Simone Biles, Mike Trout, and Carli Lloyd. Jim Gray MD of Meridian, Mississippi urges people to not be surprised if more names join them too as the U.S. is still consistently producing incredible athletes.