Frank Gusenberg (October 11, 1893 – February 14, 1929) was an American contract killer and a victim of the Saint Valentine's Day massacre in Chicago, Illinois.

With little parental supervision, Gusenberg and his elder brother Peter began committing petty crimes with Bugs Moran.

After O'Banion was murdered in November 1924, most likely by rival members of the Johnny Torrio-Al Capone organization, the Gusenberg brothers joined Hymie Weiss in getting revenge on the Capone-Torrio Gang.

Frank Gusenberg participated in the gargantuan drive-by shooting in the North Side performed on Capone's headquarters, the Hawthorne Hotel in Cicero, Illinois, riddling it with thousands of bullets on September 20, 1926.

According to many accounts, the second to last car stopped in front of the hotel restaurant where Capone was cowering and Gusenberg's brother, Pete, emerged, clad in a khaki Army shirt, brown overalls, and carrying a Thompson submachine gun fitted with a 100-round capacity drum.

Kneeling in front of the doorway, Gusenberg emptied the entire drum into the restaurant, and then casually strolled back to his car, which then sped off to safety.

Al Capone had Pasquale "Patsy" Lolordo installed as head of the influential fraternal organization Unione Siciliane.

By late 1928, the leader of the North Side Gang, Bugs Moran, struck an alliance with Al Capone's rival Joe Aiello.

Two of the men, dressed as police, entered the garage, pretending they were conducting an ordinary raid, and lined Moran's associates up against the wall.