After Masters is murdered by the "Strawhan Gang," O'Neil—who had been taught to shoot by his owner—sets out on a "vengeance trail" to hunt down the killers.
In 2013, writer Simon Spurrier and artist Jeff Stokely revived the character for , transforming the pulp premise into a complex sci-fi epic. Six Gun Gorilla
The character first appeared in as an anonymous serial in the British boys' paper Wizard Magazine , published by D.C. Thomson. After Masters is murdered by the "Strawhan Gang,"
Six-Gun Gorilla by Si Spurrier – Parts 1-4 of 6 (spoilers) Six Gun Gorilla
A gorilla named O'Neil is kidnapped from Africa and sold to a Colorado prospector, Bart Masters.