Captain Grammel is one of the minor antagonists of Book 3, Atherton: The Dark Planet. Captain Grammel is often regarded as an anomaly, being mentally unstable. He enjoys eating Cleaner meat and wears rubber soled shoes so he can sneak up on people. He is also described in the book as having a sandpapery, booming laugh.

At the end of Book 3, Captain Grammel is thrown overboard by his mutinying crew.