He was a recording artist and songwriter himself, but he also played pivotal roles in the careers of Bob Dylan and Janis Joplin.Bob Neuwirth, who had credentials as a painter, recording artist, songwriter and filmmaker, but who also had an impact as a member of Bob Dylan’s inner circle and as a conduit for two of Janis Joplin’s best-known songs, died on Wednesday in Santa Monica, Calif. He was 82.His partner, Paula Batson, said the cause was heart failure.Mr. Neuwirth had a modest, eclectic string of albums to his credit, including his debut, simply titled “Bob Neuwirth,” in 1974, as well as a 1994 collaboration with John Cale called “Last Day on Earth” and a 2000 collaboration with the Cuban composer and pianist José María Vitier, “Havana Midnight.” But he was perhaps better known for the roles he played in the careers of others, beginning with Mr. Dylan.Mr. Neuwirth said that he first encountered Mr. Dylan at the Indian Neck Folk Festival in Connecticut in 1961. Mr. Dylan was still largely unknown but, Mr. Neuwirth said years later, the singer caught his eye “because he was the only other guy with a harmonica holder around his neck.”The two hit it off, and Mr. Neuwirth became a central figure in the circle that coalesced around Mr. Dylan as his fame grew. When Mr. Dylan held court at the Kettle of Fish bar in Greenwich Village in the early 1960s, Mr. Neuwirth was there. When Mr. Dylan toured England in 1965, Mr. Neuwirth went along. A decade later, when Mr. Dylan embarked on his Rolling Thunder Revue tour, Mr. Neuwirth was instrumental in putting the band together.Mr. Dylan’s contemporaries and biographers have described Mr. Neuwirth’s role in various ways.“Neuwirth was the eye of the storm, the center, the catalyst, the instigator,” Eric Von Schmidt, another folk singer active at the time, once said. “Wherever something important was happening, he was there, or he was on his way to it, or rumored to have been nearby enough to have had an effect on whatever it was that was in the works.”From left, Bob Dylan, Mick Ronson and Mr. Neuwirth performing in Toronto in 1975 as part of Mr. Dylan’s Rolling Thunder Revue tour, for which Mr. Neuwirth was instrumental in putting the band together.Frank Lennon/Toronto Star via Getty ImagesIt has often been suggested that as Mr. Dylan assembled his distinctive persona while climbing to international fame, he borrowed some of it, including a certain attitude and a caustic streak, from Mr. Neuwirth.“The whole hipster shuck and jive — that was pure Neuwirth,” Bob Spitz wrote in “Dylan: A Biography” (1989). “So were the deadly put-downs, the wipeout grins and innuendos. Neuwirth had mastered those little twists long before Bob Dylan made them famous and conveyed them to his best friend with altruistic grace.”Mr. Neuwirth, Mr. Spitz suggested, could have ridden those same qualities to Dylanesque fame.“Bobby Neuwirth was the Bob Most Likely to Succeed,” he wrote, “a wellspring of enormous potential. He possessed all the elements, except for one — nerve.”Mr. Dylan, in his book “Chronicles: Volume One” (2004), had his own description of Mr. Neuwirth.“Like Kerouac had immortalized Neal Cassady in ‘On the Road,’ somebody should have immortalized Neuwirth,” he wrote. “He was that kind of character. He could talk to anybody until they felt like all their intelligence was gone. With his tongue, he ripped and slashed and could make anybody uneasy, also could talk his way out of anything. Nobody knew what to make of him.”Ms. Joplin, too, benefited from Mr. Neuwirth’s influence. Holly George-Warren, whose books include “Janis: Her Life and Music” (2019), said that Mr. Neuwirth and Ms. Joplin met in 1963 and became fast friends.Mr. Neuwirth performing in Brooklyn in 1999. Hiroyuki Ito/Getty Images“In 1969, he taught her Kris Kristofferson’s ‘Me and Bobby McGee’ after he heard Gordon Lightfoot play the then-unknown song at manager Albert Grossman’s office,” Ms. George-Warren said by email. “He quickly learned it and took it to Janis at the Chelsea Hotel.”Her recording of the song hit No. 1 in 1971, but Ms. Joplin was not around to enjoy the success; she had died of a drug overdose the previous year.Mr. Neuwirth was also involved in “Mercedes Benz,” another well-known Joplin song that, like “Bobby McGee,” appeared on her 1971 album, “Pearl.” He was at a bar with her before a show she was doing at the Capitol Theater in Port Chester, N.Y., in August 1970 when Ms. Joplin began riffing on a ditty that the poet Michael McClure would sing at gatherings with friends. Mr. Neuwirth began writing the lyrics the two of them came up with on a napkin.She sang the song at the show that night, and she later recorded it a cappella. She, Mr. McClure and Mr. Neuwirth are jointly credited as the writers of the song, which on the album is less than two minutes long.Ms. George-Warren said that this anecdote was revelatory: Mr. Neuwirth nudged along the careers of artists he admired, including Patti Smith, in whatever ways came to mind.“Though Bob was renowned for his acerbic wit — from his days as aide-de-camp to Dylan and Janis — when I met him 25 years ago, he epitomized kindness, mentorship and curiosity,” she said. “That is the unsung story of Bob Neuwirth.”Robert John Neuwirth was born on June 20, 1939, in Akron, Ohio. His father, also named Robert, was an engineer, and his mother, Clara Irene (Fischer) Neuwirth, was a design engineer.He studied art at the School of the Museum of Fine Arts in Boston and dabbled in painting over the decades; in 2011 the Track 16 gallery in Santa Monica presented “Overs & Unders: Paintings by Bob Neuwirth, 1964-2009.”After two years at art school, he spent time in Paris before returning to the Boston area, where he began performing in coffee houses, singing and playing banjo and guitar.He appeared in D.A. Pennebaker’s 1967 Dylan documentary, “Dont Look Back,” as well as in “Eat the Document” (1972), a documentary of a later tour that was shot by Mr. Pennebaker and later edited by Mr. Dylan, who is credited as the director, and Mr. Dylan’s “Renaldo & Clara” (1978), most of which was filmed during the Rolling Thunder tour. He also appeared in “Rolling Thunder Revue: A Bob Dylan Story,” the 2019 Martin Scorsese film.Mr. Neuwirth was a producer of “Down From the Mountain” (2000), a documentary, directed in part by Mr. Pennebaker, about a concert featuring the musical artists heard in the Coen Brothers’ movie “O Brother, Where Art Thou?”“It’s all about the same to me,” he said, “whether it’s writing a song or making a painting or doing a film. It’s all just storytelling.”Mr. Neuwirth, who lived in Santa Monica, is survived by Ms. Batson.Mr. Neuwirth could be self-deprecating about his own musical efforts. He called his collaboration with Mr. Vitier, the Cuban pianist, “Cubilly music.” But his music was often serious. The Cale collaboration was a sort of song cycle that, as Jon Pareles wrote in The New York Times when the two performed selections in concert in 1990, “added up to a shrug of the shoulders in the face of impending doom.”“Instead of breast-beating or simply wisecracking,” Mr. Pareles wrote of the work, “it found an emotional territory somewhere between fatalism and denial — still uneasy but not quite resigned.” More