Leonard Simon Nimoy ( NEE-moy; March 26, 1931 – February 27, 2015) was an American actor and director, famed for playing Spock in the Star Trek franchise for almost 50 years. This includes originating Spock in the original Star Trek series in 1966, then Star Trek: The Animated Series, the first six Star Trek films, Star Trek: The Next Generation, the 2009 Star Trek film, and Star Trek Into Darkness. Nimoy also directed films, including Star Trek III: The Search for Spock (1984), Star Trek IV: The Voyage Home (1986), and Three Men and a Baby (1987), and his career included roles in music videos and video games. In addition to acting and filmmaking, Nimoy was a photographer, author, singer, and songwriter.

Nimoy's acting career began during his early twenties, teaching acting classes in Hollywood and making minor film and television appearances throughout the 1950s. From 1953 to 1955, he served in the United States Army as a Staff Sergeant in the Special Services, an entertainment branch of the American military. He originated and developed Spock beginning with the February 1964 Star Trek television pilots "The Cage" and "Where No Man Has Gone Before", through series' end in early 1969, followed by eight feature films and guest appearances in spin-offs. From 1967 to 1970, Nimoy had a music career with Dot Records, with his first and second albums mostly as Spock. After the original Star Trek series, Nimoy starred in Mission: Impossible for two seasons, hosted the documentary series In Search of..., appeared in Columbo, and made several well-received stage appearances.

Nimoy's portrayal of Spock made a significant cultural impact and earned him three Emmy Award nominations. His public profile as Spock was so strong that both his autobiographies, I Am Not Spock (1975) and I Am Spock (1995), were written from the viewpoint of coexistence with the character. Leonard Nimoy played the elder Spock, with Zachary Quinto portraying a younger Spock, in the 2009 Star Trek reboot film, directed by J. J. Abrams. In 2010, Nimoy announced that he was retiring from playing Spock, citing both his advanced age and the desire to give Quinto full media attention as the character. His final role as Spock was in the 2013 sequel, Star Trek Into Darkness.

Nimoy died in February 2015 after a long case of chronic obstructive pulmonary disease (COPD). His death was international news and was met with expressions of shock and grief by fans, Star Trek co-stars, scientists, celebrities, and the media. An asteroid was named 4864 Nimoy in his honor. For the Love of Spock (2016) was produced by his son Adam about his life and career, and Remembering Leonard Nimoy (2017) was produced by his daughter Julie about his illness.