| Fighter | Record | Last Bout |
|---|---|---|
| Joe Soto | 18-7-0 | 2018-02-03 |
| Joe Stevenson | 33-16-0 | 2011-06-26 |
| Joel Sutton | 2-4-1 | 1995-09-08 |
| John Salter | 14-3-0 | 2010-08-28 |
| Jorge Santiago | 25-12-0 | 2013-02-16 |
| Jose Souza | 9-1-0 | 2026-05-30 |
| Joseph Sandoval | 7-7-0 | 2012-01-20 |
| Josh Samman | 13-4-0 | 2016-07-13 |
| Josh Sampo | 11-5-0 | 2015-05-23 |
| Josh Shockley | 11-4-0 | 2015-02-22 |
| Josh Shockman | 6-3-0 | 2006-11-18 |
| Josh Stansbury | 4-8-0 | 2017-06-25 |
| Josh Stuart | 1-4-0 | 1998-03-13 |
| Julian Sanchez | 0-1-0 | 1996-09-20 |
| Julija Stoliarenko | 11-10-2 | 2025-08-09 |
| Junior Dos Santos | 21-9-0 | 2020-12-12 |
| Justin Salas | 12-7-0 | 2016-03-05 |
| Justin Scoggins | 11-5-0 | 2018-07-14 |
| Kalib Starnes | 17-11-1 | 2008-04-19 |
| Kamal Shalorus | 9-5-2 | 2012-05-15 |
| Karine Silva | 19-7-0 | 2026-04-18 |
| Kazushi Sakuraba | 26-17-1 (2 NC) | 1997-12-21 |
| Ken Shamrock | 28-17-2 | 2006-10-10 |
| Ken Stone | 11-4-0 | 2012-08-11 |
| Kerry Schall | 24-13-0 (1 NC) | 2005-11-05 |
| Ketlen Souza | 17-6-0 | 2026-06-06 |
| Kiru Sahota | 12-3-0 | 2024-11-23 |
| Klaudia Sygula | 8-3-0 | 2026-09-05 |
| Kody Steele | 8-1-0 | 2026-05-02 |
| Krzysztof Soszynski | 26-12-1 | 2011-12-10 |
| Kyle Stewart | 11-3-0 | 2019-07-27 |
| Laureano Staropoli | 9-5-0 | 2021-10-23 |
| Leandro Silva | 20-6-1 (1 NC) | 2016-09-03 |
| Leon Shahbazyan | 12-5-0 | 2026-06-20 |
| Leonardo Santos | 18-7-1 | 2022-08-20 |
| Leslie Smith | 10-7-1 | 2017-07-16 |
| Liliya Shakirova | 8-2-0 | 2020-10-24 |
| Liudvik Sholinian | 9-4-1 | 2022-11-05 |
| Livinha Souza | 14-4-0 | 2021-10-23 |
| Lodune Sincaid | 15-9-0 | 2005-04-09 |
| Louie Sutherland | 11-6-0 | 2026-08-08 |
| Louis Smolka | 17-9-0 | 2022-05-14 |
| Luana Santos | 11-2-0 | 2026-06-20 |
| Lucia Szabova | 12-0-0 | 2026-10-31 |
| Luis Saldana | 16-7-1 | 2022-08-20 |
| Lukasz Sajewski | 13-3-0 | 2016-10-08 |
| Luke Sanders | 13-5-0 | 2021-05-01 |
| Mackens Semerzier | 8-4-0 (1 NC) | 2012-03-02 |
| Maia Stevenson | 6-5-0 | 2018-02-03 |
| Mairon Santos | 18-1-0 | 2025-12-06 |