Six: Gun Gorilla

In the original pulp ending, O'Neil dies immediately after killing his nemesis, Tutt Strawhan. 2. Modern Reimagining (2013)

Six-Gun Gorilla by Si Spurrier – Parts 1-4 of 6 (spoilers) Six Gun Gorilla

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 the original pulp ending, O'Neil dies immediately

A gorilla named O'Neil is kidnapped from Africa and sold to a Colorado prospector, Bart Masters. In the original pulp ending