Daniel Sutter

From Memory Alpha, the free Star Trek reference.

Daniel Sutter was an ensign who served as an engineer aboard the USS Enterprise-D in 2368, and father to Clara Sutter. He had been in Starfleet for over eight years.

He became very concerned when his daughter Clara begin playing with an imaginary friend named Isabella, who Clara insisted was real. He brought the child to Deanna Troi for counseling. Troi informed that she was just making up the friend because she was lonely. Both Sutter and Troi were shocked to find out the Isabella was real. She was an alien in Human form. (TNG: "Imaginary Friend")

Daniel Sutter was played by Jeff Allin.