| Tricon, the 24th World Science Fiction Convention | |
| Venue: | Sheraton Cleveland |
| Dates: | 1–5 September 1966 |
| Filing: | Non-profit |
| Attendance: | ~850 |
The 24th World Science Fiction Convention (Worldcon), also known as Tricon, was held on 1–5 September 1966 at the Sheraton-Cleveland in Cleveland, Ohio, United States. Officially, the convention was hosted by three cities in the region: Cincinnati, Ohio, Cleveland, Ohio, and Detroit, Michigan; hence the name "Tricon".
The three co-chairmen of that Worldcon each represented their city's fandom; they were Ben Jason of Cleveland, Howard DeVore of Detroit, and Lou Tabakow of Cincinnati.
Attendance was approximately 850.
At the convention, Gene Roddenberry premiered both pilot episodes, "The Cage" and "Where No Man Has Gone Before", for his upcoming NBC TV series Star Trek.