James Green aka Sudden is a fictional character created by an English author Oliver Strange in the early 1930s as the hero of a series, originally published by George Newnes Books Ltd, set in the American Wild West era. Oliver Strange died in 1952, and the series was revived by Frederick H. Christian in the 1960s.
The books are centred around a gunfighter in the American Wild West, who is in search of two men who cheated his foster father. Jim the young man promises his dying father that he will find the two and take revenge. He gives the name James Green to himself (his real first name,we find out in Llaw o' the Lariat,is Donald) and in time gets accused of a robbery himself and becomes an outlaw.
The series details the adventures of a gunfighter who earns the nickname "Sudden" because of his lightning speed with a gun. Sudden is also characterized as an intelligent man who is respectful of the law, unwilling to use a gun unless absolutely necessary, humanitarian, brave, and strong.