Andrzej Stanisław Badeński was a Polish sprinter who specialized in the 400 metres. He won a bronze medal in that event at the 1964 Summer Olympics, and won the gold medal in that event at the European Indoor Championships in 1968 and in 1971.
Louis Jacobus van Zyl, better known as L. J. van Zyl, is a South African athlete competing in the 400 metre hurdles. He is the South African record holder in the event with a personal best of 47.66 seconds, which he achieved twice, three months apart. His time ranks him in the all-time top 25. He is a three-time African Champion in the event and competed for his country at the 2008, 2012 and 2016 Summer Olympics.
Rabah Mahhamed Yousif Bkheit (born 11 December 1986) is a Sudanese-born British track and field athlete, who initially competed for Sudan before obtaining British citizenship.
Isaac Makwala is a Botswana sprinter who specializes in the 400 metres.
David Kitur is a retired Kenyan runner, who specialised in 400 metres.
Simon Kemboi is a retired sprinter from Kenya. He specialised in 400 metres. He is a World Championships and African Championships medalist, and competed at the Olympics.
Anna Vasylivna Ryzhykova, nee Yaroshchuk is a Ukrainian track and field athlete who specialises in the 400 metres hurdles. At the European Athletics Championships, she won silver medals in 2012 and 2018, and bronze in 2022. Ryzhykova placed fifth at the 2020 Tokyo Olympics.
Luguelín Miguel Santos Aquino is a Dominican sprinter, who specialises in the 400 m. He was the silver medallist in the event at the 2012 London Olympics at the age of eighteen. His personal best is 44.11 seconds.
Karsten Warholm is a Norwegian sprinter who competes in the 400 metres and 400 m hurdles. He is the 2020 Tokyo Olympic champion, a three-time world champion and the world record holder in the latter event.
Janieve Russell is a Jamaican track and field athlete who competes mainly in the 400 metres hurdles and the 400 metres sprint. She won an Olympic bronze medal in the 4 × 400 m relay in Tokyo 2021, where she also finished fourth in the 400m hurdles final in a personal best of 53.08 secs. She is a four-time Commonwealth Games gold medallist, winning the 400m hurdles title in 2018 and 2022, and the 4 × 400 m relay in 2014 and 2018. She has also won two relay silvers at the World Championships and a relay gold at the World Indoor Championships.
Luiz Altamir Lopes Melo is a Brazilian swimmer.
Abderrahman Almoubarrake Samba Alsaleck is a Qatari male track and field athlete who specialises in the 400 metres hurdles. He was born and grew up in Saudi Arabia but chose to represent Mauritania – his father's homeland – before eventually switching allegiance to Qatar and moving to Doha in 2015. He became eligible to compete for his adopted country in May 2016. He was the second person to run the 400m hurdle event in less than 47 seconds.
Emmanuel Kipkurui Korir is a Kenyan middle-distance runner. He is the 2020 Tokyo Olympic and 2022 World champion in the 800 metres. Korir won the silver medal in the event at the 2018 African Championships in Athletics.
Christopher O'Donnell is an Irish track and field athlete competing in sprinting events. He represented Ireland at the 2020 Summer Olympics in the Mixed 4 x 400m relay where he was part of the first ever Irish team to run in an Olympic final, and was also part of the team who reached the final of the 2022 and 2023 World Championships. He is the current Irish U20 record holder in the 400 metres, with a time of 46.54, set on 22 July 2017 at the European U20 Championships, where he finished 6th in the final. His personal best of 45.26 seconds sits joint-2nd on the Irish all-time list and he is a 5-time National 400m champion.
Alessandro Sibilio is an Italian sprinter and hurdler, who competes in the 400 metres hurdles and 400 metres. He won a gold medal at the 2018 IAAF World U20 Championships. He competed at the 2020 Summer Olympics, in 400 m hurdles.
Elija Godwin is an American athlete who specialises in the 400 metres.
Sean Bailey is a Jamaican athlete.
Alexander (Alex) Beck is an Australian Olympic athlete. He is a three time defending National champion.
Ahmed Ayoub Hafnaoui is a Tunisian swimmer. He is the African record holder in the long course 400-metre and 1500-metre freestyle, and the short course 800-metre and 1500-metre freestyle events. He competed in the 2020 Summer Olympics, where he won a gold medal in the men's 400-metre freestyle. He ranked No. 16 in the world and was the slowest qualifier for the final race but won Olympic gold with a time of 3:43.36. Hafnaoui was the only Tunisian to win Olympic gold at Tokyo 2020.
Imaobong Nse Uko is a Nigerian athlete. She competed in the mixed 4 × 400 metres relay event at the 2020 Summer Olympics. The 17-year-old won the 400 metres at the 2021 World Under 20 Championships.
Sudan 
