A god is a divine being or entity, or a supreme being. A god is known for omnipresence, omniscience, and omnipotence. And a god is also the primary or central figure of most organized religions, a point of worship and prayer.
Space:1999 (1975 - 1977) both followed the pattern laid down by Star Trek, and established its own. In the Year One story, "Black Sun," for instance, the Alphans encountered a god-like being inside the event horizon of a black hole. It was childlike and curious, but not a corporeal being as we understand it.
A more traditional God-imitator, Magus, appeared in the Year Two story "New Adam, New Eve."There, Magus was not a deity himself, but an advanced genetic scientist obsessed with developing new life.
The Fantastic Journey (1977) episode "An Act of Love" involved a culture in the Bermuda Triangle that worships a volcano as a god. Dr. Willaway (Roddy McDowall) sets the culture straight with his typical bluntness and wisdom. "You are trying to make deals with volcanoes... leave superstition behind."
On the original Battlestar Galactica (1978 - 1979), from Glen A. Larson, the Galactica encounters beings who are like Gods and devils, angels and demons in "War of the Gods." The forces of good -- god-like beings in white robes -- inhabit the Ship of Lights.
In Star Trek: The Next Generation (1987 - 1994), an early episode called "Justice" pits Captain Picard against the orbiting God of the Edo people. That God is actually a space vessel of some type, but its inhabitants are never revealed, or explained.
On Deep Space Nine (1993 - 1999), the wormhole entities, who exist outside linear time, are believed by the Bajoran people to be Gods called prophets.
A brilliant later-season episode of The X-Files (1993 - 2002), "Improbable," concerns numerology, and Burt Reynolds portrays God himself, who likens the universe to a casino where we're all gamblers.