He was called “the high priest of bebop.” With his goatee, dark sunglasses and exotic hats, Thelonious Monk was the quintessential hepcat. He patted his feet in mad rhythm while he was playing — and when his sidemen soloed, he got up and danced in circles.

Monk, who was born 100 years ago today, was also one of the greatest composers of the 20th century. The late pianist wrote about 70 songs during his career — many of which have became standards, including the most recorded jazz composition of all time, “‘Round Midnight.”

Robin Kelley, author of the biography Thelonious Monk: The Life and Times of an American Original, considers Monk the “most innovative, if not the greatest composer in the music we call jazz.”

“As a pianist, he really brought together an earlier form of stride piano — a kind of classic form of early jazz piano — with a real modern conception of the instrument,” Kelley says. “There are very few musicians who have a sound so original that no one can mimic them.”

Monk was there at the birth of bebop in the early 1940s, when the emphasis in jazz shifted from big bands to virtuosic small groups. These small groups all played Monk’s compositions and some of them, like Charlie Parker and Dizzy Gillespie, even became famous. But Monk remained relatively obscure — though he never let that get to him.

“It was so much happening,” he said in 1964 to radio host David Kidd. “You know, like, there’s always something to occupy your mind, something to occupy your time. There’s so many things to do that I even didn’t feel it. I didn’t notice it that much. If I did I, would be bitter.”

And Monk had a lot to be bitter about. He was broke most of his life, and for years he couldn’t play in New York City because the police revoked his cabaret card — a musician’s license — after he was arrested.

“Thelonious was arrested multiple times,” Kelley says. “Once for possession of marijuana. Once for possession of heroin, which wasn’t even his. And once in Delaware when he was traveling with a white woman, when he was going to a gig, and the police pulled up and stopped him.”

That white woman was the Baroness Pannonica de Koenigswarter. She was a member of the powerful Rothschild family — and a jazz enthusiast. She became Monk’s muse and patron, giving him money, driving him to gigs and letting him rehearse and record at her home.

Eventually, she had a song written about her titled “Pannonica,” after her first name. In fact, the women in Monk’s life turned up a lot in his music; “Ruby My Dear” was written for a former girlfriend, “Crepuscule with Nellie” for his wife.

Monk was born in Rocky Mount, N.C. When he was 5, his family moved to New York, and he started playing the piano a year later. Keen to begin performing, Monk dropped out of high school to go on the road backing an evangelist. Composer David Amram was a young French horn player gigging around New York in the mid-1950s when he got to know Monk….