Alvin Clarence Thomas (November 30, 1893 – May 19, 1974) was an American gambler, golfer and hustler better known as Titanic Thompson.
 He was a major witness at the 1929 Arnold Rothstein murder trial in New York City.
Jack "Legs" Diamond (born John Thomas Diamond (Disputed); July 10, 1897 – December 18, 1931), also known as Gentleman Jack, was an Irish American gangster in Philadelphia and New York City during the Prohibition era.
 A bootlegger and close associate of gambler Arnold Rothstein, Diamond survived a number of attempts on his life between 1916 and 1931, causing him to be known as the "clay pigeon of the underworld".
 In 1930, Diamond's nemesis Dutch Schultz remarked to his own gang, "Ain't there nobody that can shoot this guy so he don't bounce back?"
Now I'll Tell is a 1934 American Pre-Code drama film starring Spencer Tracy, Helen Twelvetrees, and Alice Faye.
 The film was directed and written by Edwin J. Burke and is loosely based on the autobiography of Carolyn Green Rothstein, wife of New York gambler Arnold Rothstein.
 Future child star Shirley Temple had a small role.
 The movie is also sometimes known as When New York Sleeps.
John D. Coughlin (July 2, 1874 – September 30, 1951) was an American law enforcement officer, detective and police inspector in the New York City Police Department.
 He served as head of the NYPD detectives division from 1920 until 1928 when he was removed from office amid charges of police laxity following the murder of underworld figure Arnold Rothstein.
Max "Big Maxie" Greenberg (1883–1933) was an American bootlegger and organized crime figure in Detroit, Michigan, and later a member of Egan's Rats in St. Louis.
 He oversaw the purchasing of sacramental wine from Orthodox rabbis, then allowed under the Volstead Act, which were sold to bootleggers in the St. Louis–Kansas City, Missouri area during Prohibition.
 He was also associated with mobsters in this particular method of acquiring illegal liquor including Waxey Gordon, Meyer Lansky and Arnold Rothstein.
Waxey Gordon (born Irving Wexler; January 19, 1888 – June 24, 1952) was an American gangster who specialized in bootlegging and illegal gambling.
 An associate of Arnold Rothstein during prohibition, he was caught up in a power struggle following Rothstein's death.
 Fellow Rothstein associates Charles Luciano and Meyer Lansky provided authorities with evidence that led to his imprisonment for ten years.
The Big Bankroll is a 1961 American crime film directed by Joseph M. Newman, produced by Samuel Bischoff and starring David Janssen, Dianne Foster, Diana Dors and Jack Carson.
 During the prohibition era the gangster Arnold Rothstein rises to be a major figure in the criminal underworld.
 It is also known by the alternative title King of the Roaring 20s: The Story of Arnold Rothstein.
 It was based on a book by Leo Katcher.
The Havre de Grace Racetrack was an American horse racing track on Post Road in Havre de Grace, Harford County, Maryland which operated from August 24, 1912 to 1950.
 Nicknamed "The Graw," for a time it was owned by the Harford Agricultural and Breeders Association and also by the notorious gambler, Arnold Rothstein.
Arnold Rothstein (January 17, 1882 - November 6, 1928) nicknamed "the Brain", was a Jewish-American racketeer, businessman and gambler who became a kingpin of the Jewish mob in New York City.
 Rothstein was widely reputed to have organized corruption in professional athletics, including conspiring to fix the 1919 World Series.
Michael Stuhlbarg ( ; born July 5, 1968) is an American actor.
 He played troubled university professor Larry Gopnik in the 2009 dark comedy film "A Serious Man", organized-crime boss Arnold Rothstein in the HBO television series "Boardwalk Empire" (2010–2013), René Tabard in "Hugo" (2011), Griffin in "Men in Black 3" (2012), Dr. Flicker in "Blue Jasmine" (2013), Edward G. Robinson in "Trumbo" (2015), computer scientist and inventor Andy Hertzfeld in the biopic "Steve Jobs" (2015), and Nicodemus West in superhero film "Doctor Strange" (2016).

Question: Was Arnold Rothstein an American actor, if no, then what was he?
Answer: Jewish-American racketeer