Deer is an English surname. Notable people with the surname include:
- Ada Deer (1935–2023), Native American leader
- Brian Deer (21st century), British investigative reporter
- Gary Mule Deer (born 1939), American comedian
- Gene Deer (21st century), American blues guitarist
- George Deer (1890-1974), British politician
- James Young Deer (1876-1946), Native American film actor
- Rob Deer (born 1960), American baseball player