Searched 17 events from July 25, 2015 to July 26, 2025
| Name | Gender | From | Finish Count |
|---|---|---|---|
| Brendan Obrien | Male | Denver, CO | 1 |
| Simon OBrien | Male | Longmont, CO | 1 |
| Amy O'Connell | Female | Steamboat Springs, CO | 4 |
| Celeste O'connor | Female | Fort Collins, CO | 1 |
| Peter O'Connor | Male | San Diego, CA | 1 |
| Sara Oddi | Female | Denver, CO | 1 |
| Emmanuel Odebunmi | Male | New York, NY | 1 |
| Jitka O'farrell | Female | Lakewood, CO | 1 |
| Katelyn Ogden | Female | Denver, CO | 1 |
| Christine O'Gorman | Female | Westminster, CO | 2 |
| Jamie O'Kelley | Male | Signal Mountain, TN | 1 |
| Alma Olaechea | Female | Denver, CO | 1 |
| Raymond Olexa | Male | Steamboat Springs, CO | 3 |
| Brian Oliver | Male | Littleton, CO | 1 |
| Charlie Olmstead | Male | Fort Collins, CO | 1 |
| Walter Olsen | Male | Lakewood, CO | 1 |
| Joy Olson | Female | Aspen, CO | 1 |
| Justus Olson | Male | Eagan, MN | 1 |
| Karina Olson | Female | Fort Collins, CO | 1 |
| Patrick Olson | Male | Boulder, CO | 1 |
| Bradley Olwin | Male | Berthoud, CO | 3 |
| Katie Olwin | Female | Berthoud, CO | 1 |
| Kim O'Malley | Female | Lakewood, CO | 1 |
| Nora O'Malley | Female | Broomfield, CO | 1 |
| Andy Ommen | Male | Laramie, WY | 1 |
| Louis-Marie Onfray | Male | Fort Worth, TX | 1 |
| Daniel Ontiveros | Male | Loveland, CO | 1 |
| Greg Opgenorth | Male | Westminster, CO | 2 |
| Benjamin Oppenheimer | Male | Boulder, CO | 1 |
| Tara Opsal | Female | Fort Collins, CO | 1 |
| Courtney Oran | Female | Fort Collins, CO | 1 |
| Jeff O'reilly | Male | Denver, CO | 3 |
| Rebecca Orig | Female | Lakewood, CO | 1 |
| Felix Ortega | Male | Albuquerque, NM | 1 |
| William O'ryan | Male | Columbus, OH | 2 |
| Hillary Osborne | Female | Lakewood, CO | 1 |
| John O'Shea | Male | Salt Lake City, UT | 1 |
| Hannah Osowski | Female | Colorado Springs, CO | 1 |
| Marianne Osteen | Female | Steamboat Springs, CO | 1 |
| James O'Sullivan | Male | Englewood, CO | 1 |
| Lucy O'Sullivan | Female | Boulder, CO | 1 |
| Steven Otal | Male | Levallois-Perret, France | 1 |
| Chris Otrok | Male | Columbia, MO | 1 |
| Andrew Otter | Male | Crested Butte, CO | 1 |
| Brett Overby | Male | Highlands Ranch, CO | 1 |
| Steven Pack | Male | Brooklyn, NY | 1 |
| Braddley Pakish | Male | Fort Collins, CO | 2 |
| Shawn Palandri | Male | Omaha, NE | 1 |
| Greg Palken | Male | Lakewood, CO | 2 |
| Chad Pallansch | Male | Fort Collins, CO | 1 |