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.
Sudden is portrayed as a stereotypical gunfighter: an intelligent and resourceful drifting cowboy who is respectful of the law, unwilling to use a gun unless absolutely necessary, humanitarian, brave, strong, and fair.
The series became popular for its exciting narrations combining elements of mystery, suspense, and action, with engaging characters, in a Wild West setting of dusty towns, ranches, and saloons.
Sudden's background story is not explicitly detailed but it is mentioned several times that as a young man, he promises his dying foster father that he will find the two men who cheated him and take revenge.
In Sudden—Outlawed, which goes back to the beginning of his story, he has returned to Texas from an Eastern education, but sets out on his quest for revenge on the death of his foster parent, using the name James Green.
In Sudden (1933), he is pardoned by the Governor of Arizona, Bleke, made a US deputy marshal, and subsequently sent on (typically undercover) missions to maintain law and order.