Kalidou Koulibaly (born 20 June 1991) is a professional footballer who plays as a centre-back for Saudi Pro League club Al-Hilal. Born in France, he plays for the Senegal national team.

Koulibaly began his professional club career with French team Metz in 2010, before moving to Belgian club Genk in 2012, winning the Belgian Cup in his first season. He joined Italian team Napoli in 2014, where he won the Supercoppa Italiana title; he also won the Coppa Italia in 2020.

As Koulibaly was born in France to Senegalese parents, he was eligible to represent both nations at international level, and initially played for the France national under-20 team. He later made his senior debut with Senegal in 2015, and was a member of the Senegal squad that participated in the 2017 Africa Cup of Nations. He was named to the side that represented Senegal at the 2018 FIFA World Cup the following year, and subsequently helped his team to the final of the 2019 Africa Cup of Nations. Koulibaly and Senegal then won the 2021 and finished as runner-up in the 2025 edition of the tournament, defeating Egypt and forfeiting against Morocco in the respective finals.

Koulibaly was born on 20 June 1991 to Senegalese parents in Saint-Dié-des-Vosges, France. His father worked in a textile mill in Senegal for seven days a week and never took weekends off for five years before he saved enough money to take his mother to France. He grew up in Saint-Dié-des-Vosges, revealing that: "When you grow up in this environment, you see everyone as your brother. We are black, white, Arab, African, Muslim, Christian, yes — but we are all French. We are all hungry, so let’s go have a Turkish meal together. Or tonight, let’s all go to my house and eat Senegalese food. Yes, we have differences, but we are all equal." Koulibaly says his upbringing was "heavily influenced by the multi-cultural nature" growing up.

Koulibaly revealed that he first started playing football, saying: "All the kids were running around playing football with no shoes, and I was really upset by this, I guess. My mom says that I was begging her to go to the store and buy shoes for everybody, so I could play football with them. But my mother said, “Kalidou, just take your shoes off. Go play like they do.” In the end, I threw off my shoes and went to play barefoot with my cousins — and this is where my football story begins. When we got back to France, I was playing every day in the little park by our house." His footballing career began with local club SR Saint-Dié. He then joined FC Metz in his first spell but was subsequently released at fifteen, which according to the club's Academy Manager, Denis Schaeffer, Koulibaly was let go "because he was too introverted, and his level was a little below our expectations."

Koulibaly began his career playing for his hometown club SR Saint-Dié's youth team; he spent two seasons playing for the club's team in the Championnat de France Amateur 2, before joining the youth academy of professional club Metz on 1 July 2009. While at Metz, Koulibaly helped the club's under-19 team win the 2009–10 Coupe Gambardella after the team defeated Sochaux 5–4 on penalties in the final. He also played for the club's amateur team in the Championnat de France Amateur appearing in 15 matches as Metz were crowned champions of the league finishing with 107 points.

Prior to the start of the 2010–11 season, Koulibaly signed his first professional contract agreeing to a one-year deal. He was, subsequently, promoted to the senior team by new manager Dominique Bijotat. Koulibaly made his professional debut on 20 August 2010 in a league match against Vannes. He appeared as a substitute in a 1–0 victory. Following this, Koulibaly became a first team regular for the side after dispatching the place from Nuno Frechaut. On 15 April 2011, he scored his first goal for FC Metz, as they drew 3–3 against Clermont. Three days later, Koulibaly signed a three–year contract extension with the club, keeping him until 2014. At the end of the 2010–11 season, he went on to make nineteen appearances and scoring once in all competitions. Reflecting on his first season at FC Metz, Manager Bijotat said of him, quoting: "Kalidou Koulibaly is perhaps the one who surprised the most people, while being the one who surprised me the least personally. I knew that it would come to him because it was already showing a good maturity. He's always in the right mood and does not catch fire, it's important to the job he's doing. He also knows how to analyze his own matches, which brings him to a certain regularity in his performances. Conversely, we thought Yeni Ngbakoto was the closest to the group, but it took longer to come. He had a difficult start, between suspension and injury. It took him longer to settle on the team. His game was not settled, in this area he has progressed in recent weeks and must still win in consistency."

However, at the start of the 2011–12 season, Koulibaly missed the first five league matches of the season, due to international commitments. His first appearance of the 2011–12 season came on 9 September 2011, coming as a substitute in the 60th minutes, in a 2–2 draw against Stade Lavallois. However, he served a two match suspension after being sent–off for an unprofessional conduct on Guillaume Moullec, as FC Metz lost 1–0 on 30 September 2011. Despite this, Koulibaly returned to the first team and then captained the side for the first time on 2 December 2011, in a 2–0 win over AS Monaco. He continued to regain his first team place until suspension and injury, which eventually kept him out for the rest of the 2011–12 season. At the end of the 2011–12 season, Koulibaly went on to make 23 appearances in all competitions, including 10 alongside his future international teammate Sadio Mané.