Shakespeare played a continuing role in McKellen's life when he went to Cambridge University, where he was offered a place to study English at Saint Catherine's College. This offer was withdrawn two years later, when McKellen's involvement in theatre almost completely eclipsed his studies. His work in student theatre proved invaluable, however, allowing him to work with Derek Jacobi, David Frost, and Trevor Nunn, with whom he would go on to form a lasting professional relationship. McKellen's acting pursuits were also important for another reason: as he would later explain to numerous interviewers, the theatre introduced him to other gay men, something that eased his acceptance of his own homosexuality. McKellen's identity as a gay man would prove almost as defining a characteristic of his public persona as his identity as an actor: a vocal activist, he became one of a handful of openly gay knights when he was knighted by Queen Elizabeth in 1991.

After leaving Cambridge in 1961, McKellen began his professional career at Coventry's Belgrave Theatre, where he acted in a production of A Man for All Seasons. Three years later, he was living in London and working steadily on the stage. He acted in countless productions, a number of which he also directed, and co-founded the progressive Actors' Company in 1972. He earned a score of awards and honors for his work and in 1979 was made a Commander of the British Empire. Two years later, he won international theatrical acclaim with his Tony Award-winning portrayal of Salieri in the Broadway production of Amadeus.

McKellen made his film debut in 1969 with a small role in The Promise, the same year that he caused a sensation on the stage with his portrayal of Edward II, which required him to kiss another man. It was not until 20 years later that McKellen became recognizable to international film audiences with his starring role as John Profumo in Michael Caton-Jones's Scandal (1989). Somewhat ironically, a year before gaining fame for playing one of the most infamously heterosexual public figures of the 20th century, McKellen came out to the public as a gay man during a BBC radio program. In 1993, he became recognizable to American television audiences playing gay men in And the Band Played On and Armistead Maupin's Tales of the City, two acclaimed TV miniseries; McKellen earned an Emmy nomination for his work in the former. In 1996, he earned another Emmy nomination for his supporting role in Rasputin.

That same year, the actor gained more visibility on the big screen, appearing in Six Degrees of Separation and The Ballad of Little Jo. He continued to turn in strong performances in such films as Cold Comfort Form (1995) and Jack and Sarah (1995), and he earned particular acclaim for his titular performance in Richard Loncraine's 1996 Richard III, for which he also adapted the screenplay. Following subsequent turns in Bent (1997) and Apt Pupil (1998), McKellen starred in Bill Condon's Gods and Monsters, giving a stunning portrayal of James Whale during the director's last days. His performance won a score of international accolades, including Best Actor Oscar and Golden Globe nominations and Best Actor honors from the National Board of Review.

After appearing alongside future Harry Potter Daniel Radcliffe in a TV production of David Copperfield in 1999, McKellen stepped into the shoes of the diabolical Magneto in director Bryan Singer's popular comic-book action adventure, X-Men. McKellen stuck with fantasy for his next role as well, this time on a grand scale with his Oscar nominated role as Gandalf the Grey in director Peter Jackson's long-anticipated Lord of the Rings trilogy. (information is given byYahoo!)