First Battalion Four Marines
Personnel Rosters - H&S Company
1 January - 31 December 1969
Tour Date - When Joined Company
| Name | Rank | MOS | Tour | Purple Heart | Purple Heart | KIA |
| Oberg, John R | Cpl | 0341 | 19 Jul 68 | |||
| O'Brien, Alan G | Cpl | 2531 | 5 Sep 68 | |||
| O'Brien, Robert J | Cpl | 0311 | 10 Nov 68 | |||
| Ogden, Ronald E | PFC | 0341 | 11 Jul 69 | |||
| O'Hara, D J | ||||||
| Okenquist, Carl J | PVT | 0311 | 2 Jun 68 | |||
| Olivar, George | Gy/Sgt | 0369/8511 | ||||
| Olivarez, Santiago | L/Cpl | 0351 | 14 Feb 69 | |||
| Olson, Charles R | PFC | 0351 | 31 Jul 69 | |||
| Olson, Fred W | L/Cpl | 3371 | ||||
| O'Mahoney, Terrence E | Cpl | 0341 | ||||
| Onasch, Gerald M | PFC | 0351 | ||||
| Orbino, Dennis Michael | Sgt | 0311 | 1 Mar 69 | 25 Mar 69 | ||
| Orlandella, R A | 2nd Lt | 0302 | ||||
| Ormsbee, Bruce J | PFC | 0351 | ||||
| Ortiz, Santos J | L/Cpl | 0351/0341 | 28 Dec 68 | |||
| Ouellette, John | Cpl | 3041 | 11 May 69 | |||
| Owens, Sterling L | PFC | 0311/0341 | 26 Jun 69 | |||
| Owens, Mackubin T, Jr | 1st Lt | 0302 | 18 Oct 68 | |||
| Oxendine, Robert J | L/Cpl | 2511 | 3 Jun 69 | |||