Ed Parker is a 48-year-old Hawaiian, a millionaire from his West Coast karate schools, a theoretician of the martial arts. He was one of Elvis Presley's few close friends and he may be the best source of illumination on Presley's private nature and on the phenomenon of his stardom.

"Those who had been enemies of the King is life now became sellers of the shroud," writers Parker in "Inside Elvis" a memoir of almost Gospellike earnestness. The book portrays a very different Elvis from the pistol-packing, drug-ridden egomaniac remembered by three of the singer's bodyguards in "Elvis: What Happened/," published just prior to Presley's death last August.

Presley's sudden death spurred a record-breaking demand for "What Happened?" Now Parker is journeying the talk-show circuit to publicize his version of the Elvis story, a week before thousands of fans are expected to make a pilgrimage to Memphis on the aniversary of Presley's death.

Parker is a bulky, round-faced man with a touch of innscrutability in his comfortable manner. Presley's karate instructor and unsalaried body guard off and on for 17 years, he introduced Presley to "ki" - the art of focusing physical and mental powers which, he says, helped the singer evolve from a hip-wriggling adolescent who gyrated out of nerves to polished performer who mesmerized audiences with his carefully choreographed, Karate-inspired gestures.

"He was insecure," says Parker. "He'd been a mother's boy, in a way, and when he went into the service and learned the martial arts, they helped to build his character, his confidence, and his image . . . His karate motions helped him to radiate a vibrance to the audience, and they stimulated a vibrancy in himself."

Parker claims that Presley's weakness was not food or drugs, but the love of his fans. "When his marriage failed he thought it might have a big influence on his fans. He thought it might cause them to choose sides between him and Priscilla. These things were of great concern to him.

After his divorce, and separation from his daughter Presley slid into a mental and physical decline that, according to Parker, precipitated his early death. "Elvis' body ran for four years on nervous energy alone . . . There was nothing for him to look foward to - but he always gave his best performance. He was a strong-willed individual."

Parker is franky amused by the recent allegations that the singer tried to become an FBI informer. "He wanted a badge - you know why? So he could pack a rod anywhere in the country. We all carried guns for security. He did get a narcotics badge. He was to dummy - it just a sneaky way to get a gun permit."

Parker says he has made arrangements with a "major studio" to produce a film based on his book, will play himself. It isn't Parker's first role. He recently appeared in "Revenge of the Pink Panther" as Peter Seller's sneakily beligerent Chinese house-boy.

But his immediate concern is to call attention to the book which, he says, he wrote "for Elvis's fans - so they can know him as I knew him . . . I miss Elvis, as a wonderful friend, as a brother." And, he adds, as the man to whom his fans in Memphis "will be showing their devotion - a 20th century hero."