Who is Billie Jean King? Meet the tennis legend who was honored as the coin toss captain at Super Bowl LVI

American football fans might not have immediately recognized the figure who acted as the coin toss captain during Sunday's Super Bowl as Billie Jean King, but tennis fans sure did. How can they not, when she is arguably the most celebrated tennis player on the face of the planet?

The NFL selected King, along with several other women, as the honorary coin toss captains for Super Bowl LVI in celebration of the 50th anniversary of Title IX's passage. In short, Title IX marked one of the biggest civil rights victories for women in the USA and is seen as the biggest deterrent to gender discrimination in modern times in the country.

Over the years, King's name has become synonymous with gender equality and women's empowerment in the sport. With that said, here's everything you need to know about the tennis legend:

Billie Jean King - A tennis career beyond compare

Born in 1943, Billie Jean King played her first Grand Slam at the age of 16 -- the 1959 US Open, where she lost in the first round. The American progressed slowly but steadily over the next six years, reaching two finals and three semifinals. Her first singles Grand Slam came in 1966, when she won the Wimbledon Championships.

The American won both Wimbledon and the US Open the following year, and the Australian Open and Wimbledon in 1968. The French Open finally came in 1972, thereby completing the Career Slam. King became the fifth woman in tennis history to complete the achievement. Overall, she ended up winning 12 singles Majors, four of which came before the advent of the Open Era.

King's success in the doubles category came even before she was a phenomenon in singles. Partnering with compatriot Karen Hantze Susman, she won the 1961 Wimbledon women's doubles for her first Slam. Before the Open Era began, the American had racked up six women's doubles Majors -- three with Susman, one with Brazil's Maria Bueno and two with the legendary Rosemary Casals.

She racked up another 10 titles after 1968, five with Casals, three with Martina Navratilova and two with Betty Stoeve. Unfortunately, she could not complete the Career Slam in doubles. Even though she won Roland Garros once, Wimbledon on ten occasions and the US Open five times, her best result at the Australian Open was a runner-up finish (twice).

Billie Jean King was equally prolific in mixed doubles, winning 11 Grand Slams -- four before the Open Era. She became the seventh player in history to complete a Career Slam in the category, winning four Majors on the trot between the 1967 French Open and the 1968 Australian Open. Of the 11 titles, she won eight alongside Owen Davidson and one each with Dick Crealy, Bob Hewitt and Phil Dent.

Furthermore, she also represented the US at the Fed Cup and won the event seven times. The tournament has since been renamed in her honor as the Billie Jean King Cup.

Widely regarded as one of the greatest women's players the sport has ever seen, King was inducted into the International Tennis Hall of Fame in 1987.

Billie Jean King - as prolific an activist as she was a tennis player

Billie Jean King has been as successful as an activist post-retirement

Off the tennis court, Billie Jean King was just as important and successful. In 1967, she criticized the United States Lawn Tennis Association (USTA) for not paying its players living wages. She was one of the biggest advocates of making tennis more professional and less elitist.

She then turned her attention towards closing the wage gap between the genders when it came to prize money. It was thanks to King's repeated public shaming that the US Open organizers finally agreed in 1973 to award the women's champion just as much as the men's winner. That same year, she co-founded the Women's Tennis Association (WTA) to champion the causes of women in the sport.

1973 also marked the world-famous "Battle of the Sexes". During the exhibition match, Billie Jean King took on Bobby Riggs after he had claimed that women's tennis was so inferior compared to the men's game that a 55-year-old like himself could beat the top female players. King ended up winning, and the match is considered to this day to be a significant moment in helping garner greater recognition for women's tennis.

In 1974, the 12-time Major winner founded the Women's Sports Federation (WSF) for the same purpose as the WTA but for women beyond more than just tennis. Moreover, she has also been a lifelong supporter of pro-environmental and pro-LGBTQ causes.

Sports Illustrated bestowed the Muhammad Ali Legacy award on King in 2021, in recognition of everything she has done, not only for tennis, but for all of humanity.