Actor Leonard Nimoy played Narab the Martian in the 1952 film Zombies of the Stratosphere

Unbeknownst to me, actor Leonard Nimoy, who starred as Dr. Spock in the late 1960s television series Star Trek, played the minor role of Narab
the Martian in the obscure film Zombies of the Stratosphere (Republic Studios, 1952). Here's a synopsis of the
plot, taken from the blog Classic Sci-Fi Movies:

Mars is a dying world, cooling down because it's too far from the sun. The Martians decide to knock Earth out of it's warmer orbit and put Mars there. To accomplish this, the Martians set about trying to build an H-bomb on Earth, with the reluctant help of an earth scientist with "unfriendly powers" connections. Like Radar Men the few Martians who come to Earth employ various earth thugs to do their bidding. In each episode, the Martians' latest plan is foiled. Each episode usually had a chase scene (with or without shootout). The Martians eventually succeed in getting the bomb built and armed. They flee in their rocket, but are shot down by Larry in his rocket. After the crash, the last surviving Martian, Narab, (played by Leonard Nimoy) tells Larry how to find and disarm the bomb. This he does, and the world is safe ... for now.

As the website Todd Gault's Serial Experience notes, “Of course the most famous cast member in the serial is Leonard Nimoy, almost fifteen years before wowing fans as Mr. Spock, plays a small part as a Martian invader, with few scenes and even fewer lines. Though he does get to battle the hero in the underwater knife fight.”

Pictured above: Leonard Nimoy as Narab the Martian.