It may be hard to believe these days, but Warren Beatty wasn't always Hollywood royalty. As the star turns 80 on Thursday, his standing as a respected veteran of the movie business is solid — despite his involvement in the embarrassing Best Picture snafu at this year's Academy Awards.
But, as LIFE described in a major feature about Beatty that ran in April of 1968, there was a moment when it seemed that his burgeoning career might fade. In 1961, he had broken into the business with a star turn in Splendor in the Grass from filmmaker Elia Kazan with a script by William Inge — and, as LIFE pointed out, "you cannot break in much higher than that." But he had followed that film with movies that were less than spectacular hits, and his reputation as a headstrong on-set personality and a headline-making celebrity serial monogamist (of whom LIFE declared that "the radiance of unquestioned virility pours out" when he smiled) threatened to overshadow his actual work.
All that changed with Bonnie and Clyde, the 1967 movie in which he starred with Faye Dunaway.
But it wasn't just the movie itself that set Beatty right. With low expectations for its success, the studio buried its release in its calendar. The initial response from critics and audiences was middling. It was then that Beatty accomplished the remarkable feat of convincing the public to reconsider. In fact, TIME essentially reviewed the picture twice, first as a "strange and purposeless mingling of fact and claptrap" in August of 1967 and a few months later, in a cover story, as "the sleeper of the decade," noting that the first review had made a "mistake."
By the time it was nominated for Best Picture, Beatty was set. In honor of his milestone birthday, here's a look back at LIFE best portraits of the star from the 1960s and '70s.