The Calvin and Hobbes Wiki
Alien- Zokk

Not to be confused with Planet Zokk, Zokks are an alien species in the Spaceman Spiff universe. They were featured in a single Sunday strip.

Spiff encountered a Zokk while stranded on a desert planet. As Spaceman Spiff knew about Zokks despite being unaware of the planet's name, it is implied that Zokks are present on other planets. Spiff mentions that they are solitary.

The Zokk featured is grayish-blue in color, and very similar to pterodactyls and bats in its morphology. Uniquely, though, it possesses two green antennae on top of its head.