Lucky is the name of the cat owned by Sheldon's family. When Sheldon was 8, a delivery van ran over Lucky, which gave Sheldon the perfect opportunity to replace him with a companion of his traits. His name is a misnomer of his fate, as "Lucky" was not very lucky at all.

He was mentioned in "The Griffin Equivalency" by Sheldon regarding the gang's current friendship with Koothrappali.