What is the title of the final film starring the original Star Trek cast together?

Star Trek VI: The Undiscovered Country is the final film starring the original Star Trek cast together.

The film brings William Shatner, Leonard Nimoy, DeForest Kelley, James Doohan, Nichelle Nichols, George Takei, Walter Koenig, and newcomer Christian Slater's supporting character into the last major adventure centered on the original crew. It was released in 1991, twenty-five years after the television series first premiered.

Its story follows Captain Kirk and the crew of the USS Enterprise-A as they become involved in negotiations between the Federation and the Klingon Empire. The plot was influenced by the end of the Cold War, and its title comes from a line in Shakespeare's Hamlet.

Star Trek Generations followed in 1994 and connected Kirk with Jean-Luc Picard, but it was not a full original-cast ensemble film in the same sense. Kirk appears in Generations, while several original cast members have smaller or supporting roles. The Undiscovered Country therefore serves as the concluding feature for the original television crew as a group.