Blocker can mean any of the following:
- Blocker (UK Birding Term) A bird not accessible to birders/twitchers in the UK since 1879
- Blocker (ice hockey)
- The nickname of Steve Roach, Australian rugby league footballer
- Blocker (cricket), slang for a defensive-minded batsman in cricket
- The inverse of a filter (optics). Instead of blocking everything except target color(s) like a filter does, a blocker lets everything else pass and blocks only the color(s) specified.
- Blocker, is a position in roller derby.
- Dan Blocker (1928–1972) famous American actor (Bonanza)
- Dirk Blocker (born 1957) American actor and son of Dan Blocker
- Terry Blocker is a former major league baseball player
- Blocker (G.I. Joe), a fictional character in the G.I. Joe universe
- Blocker corporation