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Pavel Andreievich Chekov (Russian: Павел Андреевич Чехов) is a fictional character in the Star Trek universe.
He is the ship's navigator from Season 2 onwards. Chekov had a tendency to refer to Glorious Mother Russia and claim that any human advancement, be it technological or cultural, originated there. He also had terrible luck and frequently ran foul of whatever physical or psychological menace the ship was facing that week, mainly because Walter Koenig had an excellent capacity for screaming. Aside from that, he and Sulu were good friends and would frequently banter about the action.
Chekov is, by far, the most junior of the regular bridge officers, but the writers justified his presence by having him act as the relief science officer whenever Spock was busy or incapacitated. In fact, Chekov would often abandon his navigation console in order to take up the science scanner if Spock had to step away, even at warp or in the middle of a battle. In Star Trek III: The Search for Spock, in a nod to this, Chekov identifies himself as the "Acting Science Officer" of the Enterprise.