What episode was written as a backdoor pilot for the character Gary Seven?

“Assignment: Earth” was written as a backdoor pilot for the character Gary Seven.

The episode follows the USS Enterprise during a trip to 1968 Earth for historical research. Kirk and Spock encounter Gary Seven, a human from the future who works to protect Earth’s history. He uses a pen-shaped device called a servo, a hidden transporter, and help from his assistant Roberta Lincoln and his cat, Isis.

Before becoming a Star Trek episode, the concept was developed as a standalone half-hour series about Seven’s missions on Earth. When no network ordered that program, the story was reshaped to include the Enterprise and became a potential spin-off launch. This format is called a backdoor pilot because an existing series introduces characters and a premise for a proposed new show.

The spin-off was never produced, but Gary Seven remained one of Star Trek’s most distinctive one-episode characters. “Assignment: Earth” was also the second season’s finale and gave Teri Garr one of her first significant television roles.