| Named By: | George Gaylord Simpson in 1927 |
| Time Period: | Late Cretaceous |
| Location: | Canada, USA |
| Size: | Estimated about 30 centimetres long |
| Diet: | Omnivore |
| Fossil(s): | Teeth |
| Classification: | | Chordata | Mammalia | Marsupialia | Ameridelphia | Didelphimorphia | |
Alphadon (meaning "first tooth") was a genus of small, primitive mammal that was a member of the metatherians, a group of mammals that includes modern-day marsupials. Its fossils were first discovered and named by George Gaylord Simpson in 1929.