Girolomo "Momo" Adamo (born 1895- died June 1956) was an Italian-American mobster and Underboss of the Los Angeles crime family.
Acording to the book, A Bad, Bad Boy in which Adamo was prominently featured, both he and his brother Joseph Adamo were born in Sicily. Momo lived in Chicago upon his arrival in the U.S. but later moved to Kansas City at the urging of Kansas City crime family boss Johnny Lazia. In Kansas City, Adamo ran a speakeasy during Prohibition called the Garden of Naples before moving to Los Angeles in 1935 along with his wife Marie and her son Paul where he became underboss to Jack Dragna in the Los Angeles crime family. His brother Joseph Adamo also became a member of the Los Angeles crime family. Both he and his brother were well connected criminals in San Diego, working with such mobsters as Frank Bompensiero. In 1950, Momo was arrested along with several members of Jack Dragna's family including Tom Dragna (brother), Louis Tom Dragna (nephew), and two men named Frank Paul Dragna (his son and nephew, respectively) after Jack fled the state after being named in the California Crime Commission report as a member of a crime syndicate in Los Angeles. The five of them were taken into custody by the Los Angeles Police Department, who believed they were responsible for bombing Mickey Cohen's home or knew who was. They were all released without being charged when the police couldn't find evidence of their involvement (Tom built the bomb, but otherwise none of them were involved).
When Jack Dragna died in 1956, the Los Angeles crime family cast a vote to see who would become the next Boss. Momo was hoping that as a long time leader and underboss he would be elected. However, lawyer-turned-mobster Frank DeSimone was elected in what is believed to have been a rigged election. He demoted Adamo and Adamo moved to San Diego shortly after. In the same year, Adamo attempted a murder–suicide by shooting his wife in the head before shooting himself. However, his wife ended up surviving. The reason for the killing isn't confirmed, but according to an unidentified police informant, Adamo's actions were out of shame from DeSimone raping Adamo's wife while being forced to watch. Adamo's wife was having an affair during their marriage and an alternative theory given is that Adamo committed these actions after finding out about it. His wife Marie, recovered and later married Frank Bompensiero.