Ultra Q (ウルトラQ, Urutora Kyū) is a 1966 Japanese tokusatsu kaiju television series created by Eiji Tsuburaya. Produced by Tsuburaya Productions, it is the first entry in the long-running Ultraman franchise (despite not featuring Ultraman) and was broadcast on Tokyo Broadcasting System (TBS) from January 2 to July 3, 1966 (the final episode was preempted until December 14, 1967), with a total of 28 episodes. This series was followed two weeks later by the more popular Ultraman (1966), the second entry in the franchise.

Ultra Q can be described as a half-hour Toho kaiju series. Executive producer Eiji Tsuburaya intended this series to be more like the American television series The Twilight Zone and The Outer Limits, featuring a variety of strange and unusual stories. After a survey, the TBS network convinced Tsuburaya Productions to add more giant monsters, as children were intensely interested in them, since Godzilla (Gojira) and Gamera were all the rage at the time (the first "Kaiju Boom" took off after Ultra Q became an enormous hit). Much like The X-Files, the series features continuing characters who investigate strange supernatural phenomena, including giant monsters, aliens, ghosts, and various other threats.

The originally planned title of this project was Unbalance, and was subsequently renamed Ultra Q mostly due to the word "Ultra" gaining popularity due to the Japanese gymnast Gold Medal recipient in the 1964 Summer Olympics using a technique named "Ultra C". The "Q" stands for "Question" and is also tied with another hit TBS series, Obake no Q-tarō, an animated series based on the manga by Fujiko Fujio. The series began production in 1964, with the premiere set for January 1966. At the time, this was the most expensive television series ever produced in Japan.