| Karl Rainer | |
| Birth Date: | 1 July 1901 |
| Position: | Defender |
| Clubs1: | FC Sturm 07 |
| Years2: | –1938 |
| Clubs2: | Vienna |
| Years3: | 1940 |
| Clubs3: | Vienna |
| Nationalyears1: | 1924–1935 |
| Nationalteam1: | Austria |
| Nationalcaps1: | 39 |
| Nationalgoals1: | 0 |
| Managerclubs1: | SC Wacker Wien |
| Managerclubs2: | Wiener AC |
| Manageryears3: | 1948–1949 |
| Managerclubs3: | Vienna |
Karl Rainer (1 July 1901 – 9 June 1987) was an Austrian international footballer and coach.[1]