Star Trek: The Next Generation

Episode: TNG 222 - Imaginary Friend

Name given by Clara Sutter to her imaginary friend in 2368. Sutter, a child aboard the U.S.S. Enterprise-D, was thought to be creating mischief and blaming it on her "imaginary friend" Isabella.

It turned out that an unusual, non-corporeal entity from the FGC-47 Nebula had entered the ship and had assumed the identity of Sutter's heretofore non-existent playmate.