Al Capone was an American gangster who led a far reaching crime syndicate during the prohibition-era. He is the only real-life person to be depicted in The Adventures of Tintin. Capone is also known in the book as "Scarface" and the "King of the Chicago Gangsters." Tintin manages to briefly capture Capone but his ultimate failure to capture Capone reflects the fact that Capone was still active at the time of writing.
Capone's rival is the devious Bobby Smiles, who heads the Gangsters Syndicate of Chicago, who Tintin does in fact manage to capture. He features as one of the chief protagonists in Tintin in America and is mentioned earlier in Tintin in the Congo where his gangsters are encountered by Tintin.