Patches was a male calico cat that Jeremy Aster kept as a pet on Earth.
When the Aster family was still living on Earth, young Jeremy used to play "Captain Patches" with the cat, pretending he was a Captain flying through space. As "Captain Patches", he crash landed on the sofa after being hit by an alien ship. Jeremy also played hide and seek with the cat and his mother, Marla Aster.
Patches, among other aspects of Aster's home life, was recreated by the Koinonians in their attempt to help Jeremy after his mother's death. The recreation was accurate as "Patches" recognized Jeremy right away. (TNG: "The Bonding")
The name of the animal who portrayed Patches is unknown.
Patches was one of the very rare examples of a calico cat who is also male.