- Star Trek: The Motion Picture
- Star Trek II: The Wrath of Khan
- Star Trek III: The Search for Spock
- Star Trek IV: The Voyage Home
- Star Trek V: The Final Frontier
- Star Trek VI: The Undiscovered Country
- Star Trek Generations
In 2370, Day participated in the takeover of Deep Space Nine. He served under the titular command of General Krim, but actually followed orders from Minister Jaro. Day tried to prevent Starfleet personnel from informing Krim that the Circle was receiving covert support from the Cardassians.
When Krim did learn of the Circle's Cardassian backing, Day resisted Krim's order to return the station to Starfleet control. In the ensuing fray, Day tried to kill Commander Benjamin Sisko, but instead killed Bajoran resistance hero, Li Nalas, when Nalas took the phaser blast meant for Sisko.