The F1 is a type of Savannah cat. F1s are considered to have 50 to 82 percent serval ancestry. The males of this category are usually the largest of the Savannah cats.
Savannah cats were created in 1986 through the breeding of a male serval to a female Siamese cat, a combination not previously seen in nature. The estimated amount of serval genetics present determines their F-class designation. F1s are the offspring of a direct pairing of serval and domestic cat and are at least 50 percent serval. They thus tend to resemble a serval more than their domestic parent. Ownership of F1s tends to be more heavily regulated than the more domestic classes.