Walter Koenig, the actor who rose to prominence for his trailblazing role as Ensign Pavel Chekov in Star Trek: The Original Series, has passed away. According to the Hollywood Reporter, Koenig died Sunday, October 25, of natural causes in his home in North Hollywood, his representative announced.

Star Trek wasn't his first time working with creator Gene Roddenberry. He played Sgt. John Delwyn in the 1963 series The Lieutenant. Before his collaborations with Roddenberry helped garner him fame, Koenig received a Bachelor of Arts in psychology from UCLA, where he transferred to after attending Grinnell College as a pre-med major.

A professor gave him the courage to pursue acting and he eventually attended Neighborhood Playhouse School of the Theatre in New York City. He was born in Chicago, Illinois but his parents moved to Manhattan when he was a child.

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His role on Star Trek not only opened up doors for a stable career, it also inspired children around the world who would send him fan mail. This would eventually help his role, which was initially supporting, become a part of the main cast. Cast to cash in on the Monkees craze, Koenig was given a mop-top wig in early episodes, until his own hair grew out long enough for him to wear the style. 

Koenig also appeared in several other shows and popular films including Goodbye, Raggedy Ann (1971), The Questor Tapes (1974), and Babylon 5 (1993).

Acting was only a part of Koenig's success. He also had a career in screenwriting and was known for working on Land of the Lost (1974), Family (1976), What Really Happened to the Class of '65? (1977) and The Powers of Matthew Star (1982). He published five books, including the autobiographies Chekov's Enterprise: A Personal Journal of the Making of Star Trek and Warped Factors: A Neurotic's Guide to the Universe.

After his time on Star Trek: The Original Series ended, Koenig was never far from the adventures of the Enterprise. He appeared in all six of the original series Star Trek movies (his delivery of "nuclear wessels" in Star Trek IV: The Voyage Home became one of the actor's best-known lines) as well as Star Trek Generations and fan films Star Trek: Of Gods and Men, Star Trek: Captain Pike, and Star Trek: Renegades.

In addition, he returned to the Star Trek universe with appearances in Star Trek: Picard and the fan series Star Trek: New Voyages. His role in Star Trek: Picard was named "Anton Chekov", implied to be Pavel Chekov's son, and named after the actor who portrayed Chekov in the J.J. Abrams films, Anton Yelchin. Koenig spoke fondly of Yelchin, saying that it was humorous watching an actual Russian actor imitate his inauthentic Russian accent.

Koenig stayed close with his Star Trek family, even serving as best man in George Takei's wedding in 2008.

The actor and writer was 90 years old.