One of the quirkier of the original Star Treks was the episode "Assignment: Earth," with Robert Lansing and Terri Garr. Lansing plays Gary Seven, who is descended from humans taken from Earth 6000 years ago and raised to keep watch over the place. While on Earth, he always carries with him a black cat with a diamond necklace. Right at the end of the episode Garr looks at the couch, and instead of seeing Isis the Cat, sees the woman she really was. The shot maybe lasted all of two seconds. Blink, and you'd miss it. Isis is uncredited in the program, but thanks to the wonders of Google I was able to find out she was Barbara Babcock, who played in other episodes of Star Trek, and was a minor star in her own right, probably best-known for being in Dallas.
Posted by Bob Wallace, who likes cats...if that's what you want to call them.