At its core, Spartan is about obstacles, about perseverance, about achieving the daunting and (seemingly) impossible. With Martin Luther King Jr. Day upon us, it's a fitting time to reflect on athletes who broke steel barriers, fought for what they believed in at all costs, and changed the world forever. These athletes continue to inspire us, motivate us, and teach us. These are some of our heroes.

Althea Gibson

THE ATHLETE

Tennis great Althea Gibson broke two remarkable barriers. In 1956 she became the first black woman to win a Grand Slam (the French Championships, now the French Open), and eight years later became the first black woman to join the Ladies Professional Golf Association (LPGA). Despite facing an incredible amount of discrimination and prejudice, she persevered and became a global icon. There was a ticker tape parade in her honor in New York City in 1957, and she has the distinction of being the first black woman to appear on the covers of Sports Illustrated and Time. Gibson paved the way for countless athletes in the decades to follow, including Venus and Serena Williams (more on them later).

THE AMAZING FACT TO KNOW

Gibson won five Grand Slam singles titles and was the first black Wimbledon champion in the tournament's 80-year history. After triumphing on the legendary grass courts, she was personally given the trophy by Queen Elizabeth II. That had never happened before.

Nathaniel Clifton

THE ATHLETE

LeBron James, Kobe Bryant, Michael Jordan, and countless other basketball stars owe their careers, at least in part, to Nathaniel "Sweetwater" Clifton, the first black man to sign an NBA contract. (Chuck Cooper was the first black player to be drafted into the league, and Earl Lloyd was the first to actually play in an NBA game.) Clifton had an eight-year career in the NBA and also briefly played baseball professionally in the Negro leagues. The New York Knicks named an award, the Sweetwater Clifton "City Spirit" Award, in his honor. The award is given to those who "epitomize the same trailblazing characteristics" that Clifton did during his life.

THE AMAZING FACT TO KNOW

In 1957, Clifton became the oldest man (34) to be named an NBA All-Star.

Kenny Washington

THE ATHLETE

In the 1920s, there were a handful of black players in the National Football League, but from 1934 until 1946 there weren't any. After an All-American college career at UCLA, he went undrafted in 1940 (clearly due to racism). In 1946, after a stint in the small-time Pacific Coast Football League, he became the first black player in the modern (post-World War II) era to sign an NFL contract. In his final game, in front of 80,000 adoring fans, Washington walked off the field to a standing ovation.

THE AMAZING FACT TO KNOW

Washington played college baseball alongside Jackie Robinson at UCLA, and many considered him to be the better baseball player. Not football — baseball.

Jason Collins

THE ATHLETE

Basketball player Jason Collins became a pioneer in the LGBT community when, following the 2012-13 NBA season, he publicly came out as gay. Why was this so significant? Because in 2014, after signing with the Brooklyn Nets, the center became the first openly gay athlete to ever play in one of the four major North American sports leagues (NFL, NBA, MLB, NHL). He inspired millions and, in 2014, Time named him one of the 100 most influential people in the world.

THE AMAZING FACT TO KNOW

Collins played high school basketball with Jason Segel, of Forgetting Sarah Marshall and I Love You, Man fame. More importantly, following Collins' announcement, SI.com — featuring him prominently — reportedly had its highest-visited day of all time, to date (3.713 million unique users).

Jesse Owens

THE ATHLETE

In 1936, Adolf Hitler was hopeful that the Summer Olympics in Berlin would establish Germany as the dominant global force in sport. What the leader of the Nazi party wasn't counting on was the brilliance of American track and field athlete Jesse Owens. Owens took home four gold medals in Berlin and, in the process "single-handedly crushed Hitler's myth of Aryan supremacy," according to ESPN.com writer Larry Schwartz. He returned to the States an international icon, but continued to endure racism the rest of his life.

THE AMAZING FACT TO KNOW

In addition to his love for track and field, Owens was passionate about baseball. He owned a Negro leagues team and briefly served as a running instructor for the New York Mets during spring training.

Wilma Rudolph

THE ATHLETE

A trailblazer in every sense of the word, Wilma Rudolph was one of the most famous black women in the world in the early 60s following a historic run at the 1960 Summer Olympics in Rome. She took home three gold medals at those Games — becoming the first American woman to win three golds in one Games — and established herself as the fastest woman in the world. Rudolph was an activist off the track, fighting for women's rights and civil rights, both causes that she was passionate about. Seven decades after her showing in Italy, she remains an icon.

THE AMAZING FACT TO KNOW

In 2014, 54 years after her exploits in Rome, Rudolph's life and accomplishments were commemorated with a U.S. postage stamp.

Muhammad Ali

THE ATHLETE

Known as simply "The Greatest," Cassius Clay was on the receiving end of hatred and prejudice when he converted to Islam, became a Muslim, and changed his name to Muhammad Ali. The fact that he opposed the Vietnam War and refused to be drafted made him an even more controversial figure, but at the same time made him a global pioneer. Convicted of draft evasion, he took his case all the way to the Supreme Court, where it was overturned. Oh yeah, and he's also probably the greatest boxer of all time.

THE AMAZING FACT TO KNOW

Ali also found success as a musician, and was nominated for two Grammy Awards.

Jackie Robinson

THE ATHLETE

Racial segregation in baseball came to its merciful end in 1947 when Jackie Robinson, playing first base for the Brooklyn Dodgers, broke the color barrier and changed the world forever. In the face of hatred and bigotry, Robinson not only survived but thrived, putting together a Hall of Fame career. He didn't just break barriers on the field; forgotten is the fact that he was the first black television analyst in MLB history and the first black vice president of a major American corporation (Chock full o'Nuts). After his death, he posthumously received both the Congressional Gold Medal and the Presidential Medal of Freedom. Generations later, Robinson is honored and remembered annually on Major League Baseball's Jackie Robinson Day.

THE AMAZING FACT TO KNOW

Upon enrolling at UCLA, Robinson became the first student in the university's history to letter in four sports: baseball, football, track, and basketball. He was also an accomplished tennis player.

Serena Williams

THE ATHLETE

Gibson was the first legendary black female tennis player, but Serena Williams took that throne and blasted her way to historic, unprecedented heights. In the face of prejudice and ridicule about not resembling the "traditional" tennis champion in both appearance and behavior, Serena stayed strong, destroyed the competition, and moved beyond just sports, expanding her empire to business and entertainment. In 2017, a mere four months after giving birth, she returned to the court and continues to be a Grand Slam favorite to this day. We'd be remiss if we didn't mention her sister, Venus, who dealt with similar unfairness and became a tremendous champion.

THE AMAZING FACT TO KNOW

Serena has won 23 Grand Slam singles title, the most by anyone — man or woman — in the Open Era of tennis.

Colin Kaepernick

THE ATHLETE

Like him or hate him, agree with him or disagree with him, admire or revile him, nobody can deny that former NFL quarterback Colin Kaepernick put his career and livelihood on the line to fight for what he believed in. Kaepernick protested police brutality and racial inequality by kneeling during the national anthem before games. He started a movement and brought both issues to the forefront of America's consciousness, but it came at a cost. Despite highly productive seasons with the San Francisco 49ers and an unquestionable skill set, Kaepernick hasn't played since the 2016 season. It's doubtful that he ever will again.

THE AMAZING FACT TO KNOW

Another multi-sport athlete! Kaepernick, a star pitcher, was drafted by the Chicago Cubs in 2009. He instead chose to pursue a football career.

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