| O'Rourke | Wm. | Yilliminning, East Narrogin | WR9 | 1912 |
| O'Rourke | Wm. | Yilliminning, East Narrogin | WR9 | 1924 |
| O'Shannessy | D. M. | Patricia Lake, Lot M. L. 804, Arrino | 1OM and 5B, 119A | 1962 |
| O'Shannessy | E. H. & B. C. | East Mt. Rupert, Wongan Hills | 0IS and 43D, 111E | 1962 |
| O'Shannessy | Est. of J. A. | M. 769, M.728 Lot 1932, Arrino | 6XS and 41D, 10E | 1962 |
| O'Shannessy | J. J. | Merolia, Block Nos. 728, 769, L. 1804, Arrino | 2OS | 1962 |
| O'Shannessy | Jas. A. | Merolia Farm, Arrino | 6XS | 1924 |
| O'Shea | A. T. | Hillview, East Beverley | OS7 and 102B, 30A | 1962 |
| O'Shea | Bernard | H. F. 12297 /74, G. L. 5209 /68, C. P. L. 22912 /55, Beverley | BS0 | 1912 |
| O'Shea | Bernard | H.F. 12297/74 G.L. 5209/68, C.P.L. 22912/55, Beverley | BS0 | 1924 |
| O'Shea | G. R. J. | Loc. Nelson 901, 85 264, 3650, 7147, 8450, Darradup, via Nannup | O0S | 1962 |
| O'Shea | J. J. | Antwerp Farm, East Beverley | OS7 | 1912 |
| O'Shea | J. J. | Antwerp Farm, East Beverley | OS7 | 1924 |
| O'Shea | J. J. | Talinga, Dangin | 6JO and 115B, 30A | 1962 |
| O'Shea | John | Banmore Farm, Cunderdin | 9OJ | 1924 |
| O'Shea | Muriel D. | Northhampton | O9K | 1924 |
| O'Shea & Sons | J. H. | Lake View, Dangin | JV6 and 11B, 112A | 1962 |
| O'Sullivan | D. | Kanowna, Kanowna | OS1 | 1912 |
| O'Sullivan | E. | Sussex 3892, Kudardup | E0S and 41B, 30E | 1962 |
| O'Sullivan | J. | Cromane Farm, Denmark | P6O and 14B, 103E | 1962 |
| O'Sullivan | J. J. | Mullewa | 2VZ | 1924 |
| O'Sullivan | J. V. | Loc. 1525, Jerramungup | JO3 and 38B, 42E | 1962 |
| O'Sullivan | M. B. & F. D. | Kanakania, Kenwick | D1S and 4B, 44A | 1962 |
| O'Sullivan | Mrs R. V. | Block 4117, Baker's Hill | KS3 | 1924 |
| O'Sullivan | Mrs. R. V. | Block 4117, Baker's Hill | KS3 | 1912 |
| O'Sullivan | S. L. | Warley Park, Duranillin | 5OS and 48B, 26A | 1962 |
| O'Sullivan | Thos. Austin | Sunbury Farm, Lot 408 Denmark, Kent Road, Denmark | QX1 | 1924 |
| O'Sullivan & Bicknell | - | Shannan, Gillingarra | OB4 | 1912 |
| O'Sullivan & Bicknell | - | Shannan, Gilliugarra | OB4 | 1924 |
| O'Sullivan & Bicknell | D. | Kanowna, Kanowna | OS1 | 1924 |
| O'Toole | A. | Aotea-Roa, Chidlow | Z0T | 1962 |
| O'Toole | Daniel | Mindarrabin, North Gnowangerup | 8OE | 1924 |
| O'Toole | J. D. | Block 14106, Nungarin | 6OT | 1912 |
| O'Toole | J. D. | Block 14106, Nungarin | 6OT | 1924 |
| O'Toole | John | Gnowangerup | O0T | 1924 |
| Oak Park Pastorial Co. | - | Moona, Goomalling | S1Z and 8B, 103E | 1962 |
| Oakey | O. L. | Block 1582, Wongan Hills | 6LO | 1912 |
| Oakey | O. L. | Block 1582, Wongan Hills | 6LO | 1924 |
| Oakley | A. E. | Mt. Phillip Station, Gascoyne | AO1 | 1912 |
| Oakley | A. E. | Mt. Phillip Station, Gascoyne | A01 | 1924 |
| Oakley | Alfred E. | Mt. Phillp Station, via Carnarvon | OZ1 | 1924 |
| Oakley | P. M. & H. W. | Glenderg Farm, Geraldton | P2O and 34D, 11E | 1962 |
| Oakley | T. W. | Sorrento Pastoral Co. Tambellup | A1V and 17D, 6E | 1962 |
| Oakman | Arthur Jas. | Fairfield, Wyalcatchem via Dowerin | A9O | 1924 |
| Oakover Pastoral Co. | - | Oakover, York | 0KK and 33C, 10A | 1962 |
| Oaks Syndicate (The) | - | Warren Road, Katanning | OS6 | 1924 |
| Oaten | J. S. | Borredale Farm, Minnievale | 3OJ | 1912 |
| Oaten | J. S. | Berredale farm, Minnivale | 3OJ | 1924 |
| Oaten | W. | Oatens Farm, Dowerin | WO4 | 1912 |
| Oaten | W. | Oaten's Farm, Dowerin | WO4 | 1924 |
