is a Belgian professional footballer who plays as a goalkeeper for La Liga club Real Madrid and the Belgium national team. Regarded as one of the greatest goalkeepers of all time, he is known for his reflexes, acrobatic saves, and command of the penalty area.

Courtois began his career with Genk and made his senior debut in 2009, at age 16; he went on to establish himself as the club's starting goalkeeper and won the Belgian Pro League. In 2011, Courtois signed for Chelsea in a transfer worth a reported £8 million (€9 million), but then joined Atlético Madrid on loan. At Atlético, Courtois won a La Liga title, the Copa del Rey, the Europa League, and reached the UEFA Champions League final. He returned to Chelsea in 2014 and won two Premier League titles and the EFL Cup. In 2018, Courtois signed for Real Madrid in a deal worth a reported £35 million (€38.8 million), becoming La Liga's most expensive goalkeeper, and where he has gone on to win three La Liga and two UEFA Champions League titles.

Courtois made his senior international debut for Belgium in 2011 at age 19, becoming their youngest senior international goalkeeper. He has since earned over 100 caps, ranking seventh-highest for appearances, while he has appeared in five major tournaments. At the 2018 FIFA World Cup, Courtois won the Golden Glove as the best goalkeeper as he helped Belgium finish third, their highest-ever finish at the competition.

Courtois has won the Ricardo Zamora Trophy three times, the Premier League Golden Glove once, and was named the third-best goalkeeper of the decade (2011–2020) by the International Federation of Football History & Statistics (IFFHS).