John Diamond (1823 – October 20, 1857), aka Jack or Johnny, was an Irish-Americandancer and blackface minstrel performer. Diamond entered show business at age 17 and soon came to the attention of circus promoter P. T. Barnum. In less than a year, Diamond and Barnum had a falling-out, and Diamond left to perform with other blackface performers. Diamond's dance style merged elements of English, Irish, and African dance. For the most part, he performed in blackface and sang popular minstrel tunes or accompanied a singer or instrumentalist. Diamond's movements emphasized lower-body movements and rapid footwork with little movement above the waist.
Diamond was most famous for a series of challenge dances. He regularly advertised that he could defeat all comers in a dancing contest, and he made good on his boasts. However, Diamond soon came to the attention of the dancer whom Barnum had replaced him with, a young black man known as Master Juba. Diamond and Juba fought dance-offs through the mid-1840s; records indicate that Juba won all but one. Accordingly, historian Robert Toll calls Diamond the "greatest white minstrel dancer".
In 1840, Diamond won $500 in a New York City jig competition. Circus proprietor P. T. Barnum took notice and hired the boy, touring him throughout the United States and Europe. Ever the showman, Barnum claimed that the dancer was a mere 12 years old (he was really 17) and billed him as the "King of Diamonds" in advertisements. Diamond performed solo and as part of a pair with blackface singers and musicians. For a time, he was teamed with "the King of Banjo players, and the Emperor of Extravaganza Singers", Billy Whitlock. Their advertisements exclaimed, "Second night of the engagement of the little 'Wirginny Nigger,' only 12 years old, who can outdance the nation, and come some 'Heel and Toe Breakdowns,' that are a caution to all darkies, and no mistake!"
Diamond earned a bad reputation among promoters and managers. One source claimed that his dancing was "considerably better than his temper and disposition." In February 1841, Diamond extorted money from P. T. Barnum and deserted his former mentor to go on a week-long binge of alcohol and women. Barnum sent a letter to his colleagues to caution them against hiring the dancer. Barnum claimed Diamond had "overdrawn the money due him to the amount of $95 and has during the last week expended a hundred dollars in brothels and haunts of dissipation & vice."