What Only True Star Trek Fans Noticed About Data's Cat
Data is one of the most beloved characters within the "Star Trek" universe. Per Nerdist, Data first appeared on the pilot episode of "Star Trek: The Next Generation" in 1987 as the only known sentient android in history. Throughout the series and its movie offshoots, Data learning and encountering a full range of human experiences and emotions was an ongoing highlight for "Star Trek" fans. Data even became a pet owner, obtaining a cat named Spot. Spot's first appearance came during the fourth season of TNG on the episode "Data's Day," which first aired on January 7, 1991, as reported by Ex Astris Scientia. Spot was referred to as "he" and was portrayed as a long-haired Somali cat. This version of Spot appeared once more, in the episode titled "In Theory," before disappearing from the show for a time.
During the sixth season of TNG, Spot reappeared on the episode "A Fistful of Datas" and became a series regular. However, sharp-eyed fans (or those with a particularly good memory) noticed something about Data's cat: it was a different Spot. Not only was Spot eventually referred to as "she," the cat was now an American shorthair with a brighter coat, new pattern, and of course shorter hair.
So why the new Spot? According to Issue 105 of the magazine Star Trek: Communicator, published in February of 1991 and quoted by Memory Alpha, not only did the first cat who portrayed Spot die between the fourth and sixth season, but producer Jeri Taylor decided Spot should give birth.
The portrayal of Spot was a multi-cat production
Per the 1991 article in Star Trek: Communicator, quoted by Memory Alpha, the new Spot was first portrayed by two cats, twin tabbies Monster and Brandy, followed by cats named Bud, Tyler, Spencer, and Zoe. The episode on which Spot gave birth, "Genesis," also featured her temporarily turning into an iguana, at which point she was played by an actual iguana named Willie. This episode also featured Spot as a hero who indirectly saves the crew of the Enterprise. The entire crew is infected by a synthetic T-cell that causes de-evolution; hence Spot's transformation to a lizard. It's only when Spot's kittens are born unaffected that Data and Captain Picard, who return from an away mission, realize that Spot's placenta protected them, giving them the idea to create an antidote using amniotic fluid from Nurse Ogawa, who was also pregnant.
While the character of Data loved Spot, famously composing an ode to his pet and even crying tears of joy thanks to a newly-implanted emotion chip when he learns Spot survived the destruction of the Enterprise in the movie "Star Trek: Generations," actor Brent Spiner was seemingly not as much of a fan. During a question and answer session (available in part on YouTube), Spiner joked that the cats who played Spot "were three of the worst actors I ever worked with" and "would not do anything you asked them to. I hated working with them, I'll be honest."