Most recently, UFC star Conor McGregor (34) has expressed his desire to return to the octagon, despite not being in a registered pool by the United States Anti-Doping Agency for any drugs test - which fighters must be in for at least six months in order to be eligible.
Tennis legend Serena Williams (41) also appeared to confirm her retirement after the US Open in September 2022, but has since gone back on her decision and announced that the chances of a return are "very high".
The likes of Tyson Fury (34), Floyd Mayweather (45) and numerous other boxers have also hung up their gloves only to return to the ring.
With retirement being such a loose term in sports right now, Flashscore looks at five of the most successful stars who have come out of retirement - and five returns that didn't quite go to plan.
Best - Michael Jordan
A basketball legend, Jordan famously retired from the sport in 1993 after three consecutive NBA championship wins with the Chicago Bulls. Rather than stopping all sport completely, he tried his hand at baseball in the minor leagues of America but found very little success.
This prompted him to return to the Bulls in 1995, where he would go on to win another three successive NBA titles as part of one of the greatest teams in basketball history, before confirming his second retirement from the sport. He actually returned a third time with the Washington Wizards in 2001, but didn't hit the heights of his earlier career.
Worst - Michael Schumacher
As one of the most decorated drivers in Formula One history, many supporters were disappointed when Schumacher retired in 2006. The German racer had won five titles with Ferrari and two with Benetton, and would ultimately return to the sport in 2010 with Mercedes.
Unfortunately, he wouldn't win any additional titles after coming out of retirement and failed to replicate the driving from his years at Ferrari, with just one podium finish. Schumacher retired again in 2012.
Best - Paul Scholes
Scholes announced his retirement from football in 2011 after an illustrious playing career, winning 10 Premier League titles and two Champions Leagues with Manchester United. He made 676 appearances for the club over a 16-year career before initially hanging up his boots and moving into coaching.
However, with an injury crisis in the United midfield and a major risk of losing the title to rivals Manchester City, Scholes came out of retirement in January 2012. City would go on to win the league that season, but the 2012/13 crown would return to United with Scholes playing a key role before properly calling time on his career.
Worst - Roberto Carlos
From one footballing legend to another, Carlos' career was just as brilliant as Scholes'. The Brazilian won the 2002 World Cup, four La Liga titles, three Champions Leagues and the UEFA Super Cup amongst many other accolades.
He retired from the sport in 2012 aged 39 but was lured out of retirement in 2015 to become player/manager of Indian Super League club Delhi Dynamos. Unfortunately, Carlos would only make three appearances for the club and left his role at the end of the season. He has since turned out for English Sunday League side Bull in the Barne United and scored in his one guest appearance - a 4-3 loss.
Best - Michael Phelps
After the London 2012 Olympics, the most decorated Olympian of all time confirmed that he would be taking a step away from swimming. Phelps ended his career with 22 medals, 18 of them gold.
He would return to the sport two years later with his sights set on Rio 2016, where he won another six medals of which five were gold. Phelps once again retired and remains the most decorated Olympic athlete of all time.
Worst - Brock Lesnar
Lesnar is best known for his performances in the WWE, but he was also the heavyweight champion of UFC in 2010 and at one time held the record for most successive title defences. He won five fights and lost three, eventually retiring after a loss to Alistair Overeem (42) and struggles with diverticulitis.
A highly anticipated return to the octagon took place in 2016 at the marquee UFC 200 event, with Lesnar beating Mark Hunt (48) in his first fight out of retirement. While the excitement for a strong stint in the UFC started to build following his win, a failed drugs test put a quick end to any future fights. The wrestler tested positive for a banned substance and was suspended by the USADA, going on to retire for a second time and having his win against Hunt overturned to a no contest.
Best - Lionel Messi
While Messi didn't officially retire from all levels of football, he did call time on his international career after Argentina lost the 2016 Copa America final to Chile on penalties. Messi missed in the shootout, and at the time had lost four major finals in nine years with his nation.
Just weeks later, though, he would reverse his decision in the hopes of finally winning a major tournament with Argentina. He would go on to win the Copa America in 2021, finishing as the top scorer and player of the tournament. Messi will now have his sights set on World Cup glory in Qatar next month as he approaches the 1000th game of a marvellous career.
Worst - Lance Armstrong
One of the more controversial entries on the list, Armstrong won seven consecutive Tour de France trophies and retired as one of the most decorated cyclists of all time. However, those titles were taken away from him following an infamous doping scandal in the years after his retirement.
Armstrong returned to the sport in 2009 but didn't win a single Tour de France and it wasn't long before he retired again.
Best - George Foreman
Foreman had a great boxing career, winning the heavyweight title and having legendary rivalries with the likes of Muhammad Ali and Joe Frazier. He lost his title to Jimmy Young in 1977 and retired from the sport shortly afterwards.
Ten years later, he returned to the sport and would eventually win back his heavyweight title, knocking out Michael Moore in 1994. Three successful title defences would follow before he lost the belt to Shannon Briggs.
Worst - Muhammad Ali
Ali is one of the most influential figures in sporting history and was a heavyweight champion on three separate occasions - a record at the time. He successfully defended his title 19 times, including against the aforementioned Foreman.
Unfortunately for Ali, his second go at boxing was a far cry from the legendary career he had built in the years prior. After his initial retirement in 1979, Ali was brought back in for two more fights - both of which he lost - including a bout against Larry Holmes. He retired again, but continued to inspire thousands through his battle with Parkinson's disease. Comeback aside he still boasts arguably the greatest legacy in sporting history.
