Nafissatou "Nafi" Thiam (French pronunciation: [tʃam]; born 19 August 1994[5]) is a Belgian athlete specialising in multi-event competition.

[12] As of March 2023, Thiam holds the Belgian records in the heptathlon and pentathlon, javelin and long jump (out and indoors).

She started participating in athletics when she was seven years old, winning her first national age group titles in 2009, by which time she was already specializing in the heptathlon.

[13] At the 2011 World Youth Championships in Athletics in Lille, France, Thiam finished fourth in the heptathlon with a total of 5366 points.

[5] On 3 February 2013, Thiam broke the junior world indoor record in the pentathlon at a meeting in Ghent with a total of 4558 points, breaking her personal best in four of the five events.

[16] On 18 July 2013, she won the gold medal in the heptathlon at the European Junior Championships in Rieti, Italy achieving a new Belgian record of 6298 points.

[5] In 2014, Thiam won the bronze medal for the heptathlon at the European Athletics Championships staged in Zürich, Switzerland.

[5] On 13 August 2016, Thiam won the gold medal for the heptathlon at the Olympic Games in Rio de Janeiro with a score of 6810 points, achieving personal best marks in five of the seven disciplines and defeating reigning Olympic and world champion Jessica Ennis-Hill of Great Britain.

At the 2024 Paris Olympic game, for the first time in several years both Thiam and Johnson-Thompson reached the start line fit and healthy.

Over the course of the two days, Thiam overcame an average high jump performance to retain once more her Olympic heptathlon title in a close contest, finishing 40 points ahead of her long-time rival who took silver.

She was coached by Belgian former decathlete Roger Lespagnard[24] for 14 years but she put an end to their collaboration in October 2022.