| Slim Lonsdorf | |
| Height Ft: | 6 |
| Height In: | 4 |
| Birth Date: | 22 March 1905 |
| Birth Place: | Manitowoc, Wisconsin |
| Death Place: | Sheboygan, Wisconsin |
| Nationality: | American |
| Career Start: | 1926 |
| Career End: | 1940 |
| Career Position: | Forward / center |
| Years1: | 1926–1932 |
| Team1: | Kohler Recreationists |
| Years2: | 1932–1933 |
| Team2: | Sheboygan |
| Years3: | 1923–1935 |
| Team3: | Sheboygan Ballhorns |
| Years4: | 1935–1936 |
| Team4: | Sheboygan Imigs |
| Years5: | 1936–1937 |
| Team5: | Sheboygan |
| Years6: | 1937–1938 |
| Team6: | Sheboygan Enzo Jels |
| Years7: | 1938–1940 |
| Team7: | Sheboygan Red Skins |
Charles Joseph "Slim" Lonsdorf (March 22, 1905 – December 10, 1987) was an American professional basketball player.[1] He played for the Sheboygan Red Skins in the National Basketball League during the 1938–39 season.[2]