It is worth noting that during late 1964 and 1965, Gene Roddenbury produced two pilots for a TV series he was trying to sell to NBC. Neither of these movies were theatrical releases, nor even ran as made-for-TV movies. As such, they're technically outside of the scope of this study. Yet, as a benchmark in where sci-fi was going, they deserve mention.
Roddenbury envisioned his TV series as a sort of Wagon Train in space. There would be a regular set of characters, meeting different adventures each week. A traveling space ship (The Enterprise) would replace the convoy of wagons as a sort of binder for the characters. Each stop along the "trail" would provide opportunities to explore social issues, such as racism, Cold War tensions, self-esteem, etc., have some fist fights, a bit of romance, then back to traveling. His formula had long legs, but a rough birth.
His first pilot, "The Cage", starred Jeffrey Hunter as Captain Christopher Pike. NBC officials thought it was too cerebral for mid-60s audiences, but they saw merit. They funded a second pilot. (less expensive, since it could re-use sets, props, costumes, etc.) This time, starring young William Shatner as Captain James T. Kirk. The second pilot had more adventure and a bare-knuckles fist fight (like westerns have), so NBC liked it. NBC wanted some changes made for the series, which did not sit well with Roddenbury. He stepped back from active participation.
While the two pilots did not air as movies, their footage was incorporated into first season which aired in 1966. Episode 3 "Where No Man Has Gone Before", used the second pilot's footage. Episodes 11 and 12, "The Menagerie" used the first pilot's footage, told as flashback with new Kirk/Spock footage as binder.
As influential as the original series of Star Trek was, it had a short life. NBC lost interest in it, and tried to kill it, twice. Fans objected and saved it (temporarily). Star Trek only ran three seasons. In syndication, however, its reruns reached a huge audience and thereby a disproportionately large influence. It became a benchmark of what sci-fi space operas could be.