| Fighter | Record | Last Bout |
|---|---|---|
| Felicia Spencer | 9-3-0 | 2021-11-13 |
| Felipe Silva | 8-2-0 | 2018-05-19 |
| Felipe dos Santos | 8-3-0 (1 NC) | 2025-03-22 |
| Floyd Sword | 12-3-0 | 2007-06-23 |
| Frank Shamrock | 23-10-2 | 1999-09-24 |
| Frankie Saenz | 13-7-0 | 2020-08-01 |
| Fredy Serrano | 3-2-0 | 2016-12-17 |
| Gable Steveson | 4-0-0 | 2026-09-19 |
| Gabriel Santos | 12-2-0 | 2025-02-08 |
| Gabriel Silva | 8-2-0 | 2020-02-29 |
| Genki Sudo | 15-4-2 | 2004-04-02 |
| George Sotiropoulos | 14-7-0 | 2013-10-19 |
| George Sullivan | 17-7-0 (1 NC) | 2018-08-25 |
| Georges St-Pierre | 26-2-0 | 2017-11-04 |
| Gerald Strebendt | 9-7-0 | 2003-09-26 |
| Gilbert Smith | 12-6-0 | 2013-04-13 |
| Gokhan Saki | 1-2-0 | 2018-07-07 |
| Gokhan Saricam | 12-2-0 | 2026-04-18 |
| Greg Soto | 9-4-0 | 2011-01-01 |
| Greg Stott | 0-1-0 | 1997-10-17 |
| Hans Stringer | 22-8-3 | 2015-07-18 |
| Hayato Sakurai | 38-13-2 | 2002-03-22 |
| Hecher Sosa | 15-1-0 | 2026-03-14 |
| Hector Sandoval | 14-4-0 | 2017-08-05 |
| Hector Santiago | 7-1-0 | 2026-08-29 |
| Henrique da Silva | 14-5-0 | 2017-09-22 |
| Igor Severino | 8-1-0 | 2024-03-23 |
| Iliarde Santos | 30-13-1 (1 NC) | 2013-10-09 |
| Ivan Salaverry | 14-9-0 | 2008-05-24 |
| Ivan Serati | 12-4-0 | 2009-01-17 |
| Jacare Souza | 26-10-0 (1 NC) | 2021-05-15 |
| Jack Shore | 17-3-0 | 2024-11-02 |
| Jacobe Smith | 12-0-0 | 2026-02-21 |
| Jake Shields | 31-9-1 (1 NC) | 2014-03-15 |
| Jamey Simmons | 7-4-0 | 2021-08-07 |
| Jamie Siraj | 14-4-0 | 2026-04-18 |
| Jason Saggo | 12-4-0 | 2017-09-16 |
| Jay Silva | 10-11-1 | 2010-01-11 |
| Jean Silva | 17-3-0 | 2026-09-12 |
| Jeka Saragih | 14-5-0 | 2025-06-07 |
| Jeremy Stephens | 29-23-0 (1 NC) | 2026-05-09 |
| Jerrod Sanders | 16-3-0 (1 NC) | 2016-07-07 |
| Jesse Sanders | 23-7-0 | 2009-04-01 |
| Jesse Strader | 5-3-0 | 2022-02-19 |
| Jin Soo Son | 9-4-0 | 2019-07-20 |
| Joaquim Silva | 14-6-0 | 2025-09-13 |
| Joby Sanchez | 11-4-0 | 2018-11-10 |
| Joe Slick | 16-5-3 | 2000-04-14 |
| Joe Solecki | 13-6-0 | 2025-01-11 |
| Joe Son | 0-4-0 | 1994-12-16 |