Walter Koenig

played Alfred Bester in Babylon 5

Bester is a senior Psi Corps agent who at one time appeared to be linked to the sinister alien race called The Shadows. Alfred Bester was named after the real science fiction author by his grandfather, Kevin Vacit, in the context of the Babylon 5 universe.

His parents were Matthew and Fiona Dexter, who were both leaders of the first resistance against the Psi Corps and had been killed by the Psi Corps whose director, Kevin Vacit, was father to Fiona. Following their deaths, he was raised as a member of the Psi Corps in cadre prime, where the Corps became both mother and father. Bester was not aware of his heritage. Being a P-12, the strongest naturally-occurring category of human telepaths, he was able to join the metasensory police and in this capacity he pushed his own agenda, not always successfully, on spacestation Babylon 5.
played Pavel Chekov in Star Trek

Chekov joined the Enterprise as a navigator. He left the Enterprise a few times, one time he had a position as a First Officer.