A friend, Scott Withers, said Ms. Blair had long-standing health complications related to a nervous system disorder known as Clippers disease.
Ms. Blair’s screen and stage credits ranged from soap operas to musicals. She was part of the Greek chorus in Woody Allen’s “Mighty Aphrodite” (1995); played the world-weary prostitute Amber (a role later changed to Angel) in the 1978 original Broadway cast of “The Best Little Whorehouse in Texas”; and performed in the flirtatious role of Curley’s wife in a 1974 revival of “Of Mice and Men” starring James Earl Jones.
But her portrayal of Valerie Clarke, the surgically enhanced striver in “A Chorus Line,” gave her original bragging rights to one of the most memorable characters in a Broadway juggernaut — which ran for more than 6,100 performances from 1975 to 1990 and has been restaged in thousands of venues around the world.
Ms. Blair set the foundations for Val’s character with a contrast of homespun perkiness — pigtails and doe eyes — and unvarnished big-city ambitions. Val’s solo song, “Dance: Ten; Looks: Three,” tells the tale of a dancer who decides her flat-chested and skinny frame will not get her jobs. She goes under the knife to enhance her bust and butt — and finds herself fending off casting directors.
“Fixed the chassis. ‘How do you do!’” sings the character Val. “Life turned into an endless medley of ‘Gee, it had to be you!’” (The song and lyrics, by Marvin Hamlisch and Edward Kleban, had a risqué refrain about body parts that gave it the nickname the “T&A song,” which some troupes reworded with semi-rhymes “This and that.”)
Ms. Blair left “A Chorus Line” in 1977 but remained part of the show’s architecture. She and the show’s choreographer and director, Michael Bennett, added some elements of her real life to Val’s character, a Vermont-born dancer who comes to New York with dreams of becoming a Rockette at Radio City Musical Hall. (The plastic surgery part, however, was invented and had nothing to do with Ms. Blair’s past.)
Like Ms. Blair — and unlike many of the other characters in the production — the character Val also was not inspired to become a dancer by “The Red Shoes,” a 19th-century Hans Christian Andersen story adapted into a 1948 film.
“Whenever I don’t seem to be getting anywhere in this business,” Ms. Blair once said, “I try to remember that I was once a chambermaid in a small motel in Vermont.”
In 1974, Ms. Blair was among the performers invited to workshops as Bennett explored an idea for a musical about dancers facing the grueling and soul-baring competition for a part in a show. Bennett asked increasingly personal questions to the group. The replies were tape-recorded and used as raw material for some of the characters as “A Chorus Line” developed.
The show opened off-Broadway in April 1975, and moved to Broadway that summer. Many reviews hailed “A Chorus Line” as a groundbreaking work of musical theater. Much attention went to the candid and deeply personal accounts shared by some characters — including stories of childhood trauma and coming out as gay — as they auditioned and sized each other up. (Ms. Blair’s character is among the eight dancers ultimately chosen for the chorus line.)
“What makes ‘A Chorus Line’ so devastatingly effective is its honesty of subject matter,” wrote New York Times theater critic Clive Barnes in a 1975 review, “so that even its faults can work for it.”
Bennett said the early concepts for “A Chorus Line” emerged from the Capitol Hill hearings over the Watergate break-in, which led to the resignation of President Richard M. Nixon in 1974.
“It’s my reaction to the falsehood and apathy that seemed to grip the country during that period,” he told the Times in 1975. “I was sick of it. I wanted to do something on stage that would show people being honest with one another.”
Pamela Blair was born Dec. 5, 1949, in Bennington, Vt. Her father worked at a company that made plastic molds; her mother was a library volunteer.
Ms. Blair moved to New York at 16 to attend a private school, the National Ballet Academy New York, where she met Bennett at a dance class. Their encounter led to her first major Broadway dance role in his 1968 musical comedy, “Promises, Promises,” with songs by Burt Bacharach.
She remained with Bennett for a dance role in his 1973 musical “Seesaw” about a mismatched romance. In 1972, she appeared in director Gower Champion’s “Sugar,” a musical adaptation of the 1959 film “Some Like It Hot.”
Other Broadway performances included a prominent role as Lt. Cmdr. Joanne Galloway in the military drama “A Few Good Men” (1989), directed by her then husband, Don Scardino. Her film roles included a doctor in “21 Grams,” a 2003 drama starring Sean Penn and Benicio Del Toro; and a doctor’s assistant in the 1996 crime thriller “Before and After” with Meryl Streep and Liam Neeson.
“I was some movie star,” she joked to Newsday in 1980 about trying to parlay “A Chorus Line” into Hollywood success. “I couldn’t get six lines in a sitcom.”
In 1996, she provided the voices of a flight attendant and a White House tour guide in the animated “Beavis and Butt-head Do America.”
She appeared on daytime television dramas such as “Another World” and “All My Children” and in TV series including “Law & Order,” “The Cosby Show” and “Sabrina, the Teenage Witch.” In 1983, Ms. Blair had a supporting role alongside Jodie Foster and Peter O’Toole in the TV film “Svengali.”
Her marriage to Scardino ended in divorce. Survivors include a sister. Most recently, Ms. Blair ran a massage studio for athletes in the Phoenix area.
In “A Chorus Line,” Ms. Blair’s character has a memorable bit about the place where she was raised, the bucolic Vermont hills about 10 miles north of Bennington. The line, in a sense, is a nod to everyone who has come to New York to reinvent themselves and chase dreams.
“As far as I’m concerned, I’m Valerie Clarke; but my parents seem to think I’m Margaret Mary Hoolihan,” said Ms. Blair’s character, Valerie. “Couldn’t you just die? I was born in the middle of nowhere. I mean, it wasn’t even a town, really. Near Arlington, Vermont.”