Hide drivers with less than 10 entries
Hide drivers who only participated in Indy 500
Ignore non-championship races
| No | Driver | Races | Active Years |
|---|
| 1261 |  O'Brien, Robert | 2 |
1952 |
| 1262 | O'Connor, Pat (Indy only) | 5 |
1954–1958 |
| 1263 | O'Rourke, Steve (Non-champ only) | 2 |
1982 |
| 1264 |  O'Sullivan, Zak | 1 |
2023 |
| 1265 |  O'Ward, Patricio | 3 |
2022–2024 |
| 1266 |  Ocon, Esteban | 168 |
2016–2018, 2020–2025 |
| 1267 | Odlum, Richard (Non-champ only) | 2 |
1952–1953 |
| 1268 | Oliver, Jackie | 61 |
1967–1973, 1977 |
| 1269 | Oliver, Mike (Non-champ only) | 3 |
1952, 1955–1956 |
| 1270 |  Olthoff, Bobby (Non-champ only) | 33 |
1968–1971 |
| 1271 | Ondet, Jean (Non-champ only) | 5 |
1945–1947 |
| 1272 | Ongais, Danny | 6 |
1977–1978 |
| 1273 |  Oppitzhauser, Karl | 2 |
1976 |
| 1274 | Oreiller, Henri (Non-champ only) | 1 |
1953 |
| 1275 | Orley, Alexander (Non-champ only) | 2 |
1952–1953 |
| 1276 | Ouvaroff, Steve (Non-champ only) | 1 |
1958 |
| 1277 | Owen, Arthur | 2 |
1959–1960 |
| 1278 | Oxton, David (Non-champ only) | 1 |
1973 |
|
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