| Oaten | W. R. B. | Locs. 20286/7, Gabbin | 4OE | 1924 |
| Oates | C. A. | Wondeela, Busselton | Y3O | 1962 |
| Oates | F. J. | Locs. 2015 and 1762-3-4-5-6, Hillcrest Tutunup and Abba River, via Busselton | 0FJ | 1962 |
| Oates | Josiah Charles | Orooroo Farm (Locs. 2017 and 2018), Tutunup | Y3O | 1926 |
| Oates | R. K. | Commonage, Kookynie | RK0 | 1912 |
| Oates | R. K. | Commonage, Kookynie | RK0 | 1924 |
| Oats | Frederick W. | Gunville, Wagin | FW1 | 1926 |
| Obagama Cattle Co. | - | Kolyeeda Station, Mt. James, Derby | F7L | 1924 |
| Obagama Cattle Co. | - | Kimbolton, Derby | ZV6 | 1924 |
| Obagama Pastoral Co. Ltd. | - | Obagama Station, Jubilee Downs, Derby | OC7 | 1924 |
| Obagarma Cattle Co. | - | Kolyeeda Station, Mt. James, Derby | F7L | 1912 |
| Obagarma Cattle Co. | - | Obagama and Jubilee Downs, Derby | OC7 | 1912 |
| Obagarma Cattle Co. | - | Kimbolton, Derby | ZV6 | 1912 |
| Oberdorfer | Frank | Minevale Farm, Coomberdale | 7FO | 1912 |
| Oberdorter | Frank | Minevale Farm, Coomberdale | 7FO | 1924 |
| Oborn | John | Quambi, Mundijong | OJ2 | 1924 |
| Oborne | D. C. | Maydon, Kendenup | 0DN and 25D, 8E | 1962 |
| Oborne | F. W. | Arundel, Tenterden | FO1 | 1924 |
| Oborne | H. S. | 13664 and 11547, Kulin | SN1 and 6D, 30E | 1962 |
| Oborne | J. W. | Hay Loc. 725, Kendenup | J0W and 31B, 119A | 1962 |
| Oborne | P. T. | Homeleigh, Tenterden | Y5O and 115B, 12E | 1962 |
| Oborne | Percy Tom | Tenterden | Y5O | 1925 |
| Oborne | S. I. | Arundel, Kendenup | S1O | 1962 |
| Oborne & Co. | L. V. | Arundel, Kendenup | FO1 and 38D, 12E | 1962 |
| Obst | I. C. & I. J. | Loc. Melbourne 474-5, Jennacubbine | 1CO and 13B, 106A | 1962 |
| Obst | V. C. | Boolerong, Dumbleyung | 0VC and 49B, 13E | 1962 |
| Ochiltree | Andrew | Greenpools, Harvey | 3QA | 1924 |
| Ockerby | C. A. | Pt. Canning Loc. 5, East Cannington | CO1 and 5B, 49A | 1962 |
| Ockerby | Joseph | Loc.1568, Wellington Mills | 0KB | 1912 |
| Ockerby | Joseph | Loc. 1568 Wellington Mills | 0KB | 1924 |
| Ockerby | Thos. | Dewsbury Park and La Grange, Kellerberrin | 0KB | 1924 |
| Ockwell | T. S. L. | Loc. 9570-1, Pemberton | Y0T | 1962 |
| Octavia Pastoral Co. | - | Octavia, York | T6F and 44C, 112E | 1962 |
| Oehm | Henry R. | Coenhill, Katanning | RO3 | 1912 |
| Oehm | Henry R. | Coenhill, Katanning | RO3 | 1924 |
| Oehm | M. (Mrs) | Lakeside, Katanning | N0M and 40B, 22E | 1962 |
| Offer | A. G. | 821, 950, 922, 1055, Balingup | 2AO and 35B, 106E | 1962 |
| Offer | Charles | Brookside, Benger | CX7 | 1912 |
| Offer | Chas. | Brookside, Benger | CX7 | 1924 |
| Offer | D. B. | Lots 45-7, Part/43, Wellington Loc. 1, Benger | CX7 | 1962 |
| Offer | E. J. | Lot 3543 or 36P, Benger | CX6 | 1962 |
| Offer | Ed | Denmark | EO3 | 1912 |
| Offer | Edward | Denmark | S03 | 1924 |
| Offer | F. I. | Henty Estate, Burekup | 0XF | 1924 |
| Offer | G. E. | Willowdene, Waroona | GZ0 | 1962 |
| Offer | George | Benjaberring | 7⊚H | 1927 |
| Offer | J. Henry | Mynotis, Benger | H07 | 1912 |
| Offer | J. Henry | Mynotis, Benger | H07 | 1924 |
| Offer | L. C. | Wellington Lot 4, Wokalup | LO4 | 1962 |
| Offer | L. E. | Maxicar, Dardannup | 4LO | 1962 |
