Eden

This is the place where Aziraphale and Crowley meet at the beginning of time, as rain makes its first appearance on the planet.

The Bentley

Crowley's car.

Chattering Order of Saint Beryl

This is a Satanic order of nuns that run the hospital where the babies are switched at the beginning of the story.

Aziraphale's Book Store

Aziraphale's bookstore specializes in rare books. It merely provides a front for Aziraphale as a second-hand book dealer. He has a personal interest in certain books.

Four Horsemen/Bikers of the Apocalypse

The Four Horsemen of the Apocalypse are War, Pollution, Famine, and Death. In Good Omens, they appear as bikers rather than typical horsemen.

Kumbolaland

An African nation that was peaceful until Scarlett/War of the Four Horsemen/Bikers of the Apocalypse arrives.

Phaeton

This is Anathema's bicycle that she is riding when she gets hit by Crowley's Bentley...