| Cosgrove | R. M. | Royslands, Kwolyn | C1R | 1924 |
| Cosgrove | R. M. | Hillside, Shackleton | C3R and 13C, 21E | 1962 |
| Cosgrove | Thos. | Commonage, Greenbushes | CY3 | 1924 |
| Cosh | A. J. | Blocks 1517, 2226, 2503, Marne | 6KA | 1924 |
| Cosh | E. C. | Block 9350, Dowerin | CO8 | 1912 |
| Cosh | E. C. | Block 9350, Dowerin | CO8 | 1924 |
| Cosh | H. L. | Emu Flat, Narembeen | L8C and 5D, 102E | 1962 |
| Cosh | James Gilmour | Parts Avon Loc. 15904, Bungulluping | VC3 | 1924 |
| Cosh | L. J. | Merrivale, Corrigin | 4LC and 20D, 119E | 1962 |
| Cosh | M. L. | 2357, Narembeen | C5L and 114B, 30A | 1962 |
| Cosh | Mrs Annie | Stoke Farm Estate, Maddington | 7YU | 1924 |
| Cosh | N. S. | Kent Loc. 1243, Ongerup | NC5 and 23A, 36B | 1962 |
| Cosh | P. J. | Wood Dale, Corrigin | PC8 and 49B, 24E | 1962 |
| Cosh | S. R. | 25759, Narembeen | SR8 and 117B, 45E | 1962 |
| Cossey Bros. | - | Glenthorne, Dowerin | TB5 | 1924 |
| Costa | Jas. & Yani, Giovanni | The Gardens, Leonora | 9CY | 1924 |
| Costello | H. C. & P. | East Brookton | 3GT | 1928 |
| Costello | P. C. | Lake Matilda, Kendenup | 9RZ and 21D, 20E | 1962 |
| Costello | V. | 4490 and 1793, Kendenup | 4VC and 11A, 36B | 1962 |
| Cotrona | L. | Little Coogee, N. Wanneroo | CV7 and 29A, 4B | 1962 |
| Cottam | L. T. | Hope Vale, Bolgart | KT0 | 1924 |
| Cotter | D. J. & E. G. | Mingelow, Dandaragan | D9C and 16C, 50E | 1962 |
| Cotter | J. P. | Malcolm | MM7 | 1912 |
| Cotter | J. P. | Malcolm | MM7 | 1924 |
| Cotterell | Alma W. | Garden Area, P. O. Esperance | YN8 | 1924 |
| Cotterell | Ernest W. | Avon Loc. 4064, Dowerin | 8EK | 1924 |
| Cotterell | John | Yorke Valley Farm, Benjabbering | 9YC | 1924 |
| Cotterell | R. W. | York Gum Flat, Ejanding | 3CX | 1924 |
| Cotterell | Sydney H. | Chesterfield, Rockingham | S1C | 1912 |
| Cotterell | Sydney H. | Chesterfield, Rockingham | S1C | 1924 |
| Cotterill | Jas. | Montreal, Chatham Street W. Midland | 0C T | 1912 |
| Cotterill | Jas. | Montreal, Chatham Street, West Midland | 0CT | 1924 |
| Cotterill & Lupton | C. R. & H. C. E. | Portion of White Cliffs Station, Laverton | C3L and 114A, 19C | 1962 |
| Cottle | S. H. | Kalgarin, Kondinin | VK9 | 1924 |
| Cottle | S. R. | Badgetopping, Kellerberrin | V9K and 28B, 23E | 1962 |
| Cotton | E. C. | Narrikup | 0YC | 1924 |
| Cotton | E. W. | Hope Farm, Muresk | T7C | 1912 |
| Cotton | E. W. | Hope Farm, Muresk | T7C | 1924 |
| Cotton | Geo. | Dwellingup | KT2 | 1924 |
| Cotton | T. W. R. | Rusmore, Boyup Brook | O0R | 1927 |
| Cotton & Co. | S. A. | Piednippie Downs, Dalyup, via Esperance | 7CL and 104B, 42E | 1962 |
| Cottrell | C. C. & J. I. | Yorke Valley Farm, Benjabbering | 9YC and 28C, 29E | 1962 |
| Cottrell | H. J. | Broadacres, Benjabbering | VM3 and 45D, 9E | 1962 |
| Cottrell | L. E. | 2215, Hyden | LC5 and 42C, 103A | 1962 |
| Cottrell | R. W. | York Gum Flat, Ejanding via Dowerin | 3CX | 1912 |
| Coucher | R. G. S. | The Farm, Williams | R2C | 1912 |
| Coucher | R. G. S. | The Farm, Williams | R2C | 1924 |
| Couchman | Wilfred George Chalmers | Avon Locs. 14332, 24308, 24706, Kalkalling, Lake Brown Siding | W2G | 1926 |
| Coughlan | D. A. | Coronation Hotel, Queens Park | DC0 and 84D, 50E | 1962 |
| Coughlan | Wm. V. | Commonage, Fremantle, Central Avenue, Chester Park, S. Fremantle | OV9 | 1924 |
