| Full Name: | Karl Adolf Clarence Hammar |
| Nationality: | Swedish |
| Birth Place: | Solna, Sweden |
| Death Place: | Haninge, Sweden |
| Classes: | 1924 Olympic Class Monotype, 8 Metre |
| Show-Medals: | yes |
Karl Adolf Clarence Hammar (23 June 1899 – 31 December 1989) was a Swedish sailor who competed in the 1924 Summer Olympics and in the 1928 Summer Olympics.[1]
In 1924 he finished sixth in the Olympic Monotype. Four years later he was a crew member of the Swedish boat Sylvia which won the bronze medal in the 8 metre class.