Jazz royalty is a term encompassing the many jazz musicians who have been termed as exceptionally musically gifted and informally granted honorific, "aristocratic" or "royal" titles as nicknames. The practice of affixing honorific titles to the names of jazz musicians goes back to New Orleans at the start of the 20th century, before the genre was commonly known as "jazz".
In New York City in the 1920s, Paul Whiteman was billed as the "King of Jazz". His popular band with many hit records arguably played more jazz-influenced popular music than jazz per se, but to the dismay of many later jazz fans, Whiteman's self-conferred moniker stuck, and a film The King of Jazz starring Whiteman and his band appeared in 1930. The "King of Jazz" title was a publicity stunt in 1923 by an instrument manufacturer that Whiteman endorsed.
The well-tended Prince of Darkness persona is gone this way
Duke Ellington referred to him as 'Maharajah of the keyboard'