What wild cat is the cousin to silver tabby?

The term "silver tabby" usually refers to a domestic cat with a particular coat pattern and color. There's no single wild cat that's directly considered a "cousin" to silver tabbies.

However, all domestic cats are descended from the African wildcat (Felis silvestris lybica). So, in a broader sense, the African wildcat is the ancestor of all domestic cats, including silver tabbies.

You might be thinking of the Asiatic wildcat (Felis silvestris), which is closely related to the African wildcat. This wildcat species has a similar striped pattern to some silver tabbies, but it's much more solidly colored and doesn't typically have the silver sheen.

So, while there isn't a direct "cousin," the African wildcat is the ultimate ancestor of silver tabbies, and the Asiatic wildcat shares some similar physical traits.