In Rocky III, Clubber Lang’s given first name is James.
The character is identified as James “Clubber” Lang, the aggressive Chicago southpaw played by Mr. T. Lang is Rocky Balboa’s principal opponent in the film and rises to the world heavyweight title after defeating Rocky in their first bout.
Lang’s backstory explains his fierce personality: he spent much of his youth in orphanages and on Chicago’s South Side, later serving time for aggravated assault. He discovers boxing as an outlet for his anger and becomes a powerful, intimidating contender. His character was loosely influenced by real boxers including Sonny Liston, Larry Holmes, and George Foreman.
Viewers most often remember the nickname “Clubber” rather than the given name, which makes James an easy detail to miss. The name also appears in later Rocky material and in a version of the Rocky Balboa script, where Lang is addressed by his given name.