Al Pacino has been honored with the American Film Institute's Life Achievement Award.The 'Scarface' actor, who received the acting institution's highest honor at Los Angeles' Kodak Theatre last Thursday, was left visibly moved as a series of Hollywood stars paid tribute to him.Upon collecting his award, Pacino said: "I need a character. I don't think of myself as being able to do anything. Seeing my life in the movies, I have one question. And that is, 'Why aren't I in rehab?!'"By age 3, I was doing Al Jolson (legendary singer who starred in the first 'talking' film). I found, in the theatre, this place I could go to. I found this peace."It means so many things to be honoured like this. It feels great".The three-hour gala featured clips from Pacino's biggest films including 'The Godfather', 'Scent of a Woman' and 'Serpico'.Director Oliver Stone, who wrote 'Scarface' in which Pacino starred as a violent drug dealer, paid tribute to one of Pacino's most famous lines.Stone said: "Al has a wicked sense of humour and a great, if misunderstood,heart."It is with great love and respect that I say goodnight to the bad guy."Jamie Foxx, who starred alongside the 67-year-old in 'Any Given Sunday',hailed him as "the greatest actor in the world".Andy Garcia, who worked with Pacino on 'The Godfather: Part III', said: "The depth of your artistry is only more overwhelmed by the generosity of your spirit and your warmth. You're Van Gogh. You're Modigliani. That's who you are."Robin Williams, who was treated for alcoholism last year, joked: "I would like to raise a glass to you, but that would be 11 months out the window."Past recipients of the prestigious award include Sir Sean Connery, Martin Scorsese, Steven Spielberg, Elizabeth Taylor, Alfred Hitchcock, Bette Davis and Jack Nicholson.Pacino is best known for playing mafia boss Michael Corleone in the 'Godfather' movie series.He won a Best Actor Oscar for 'Scent of a Woman' in 1993 for his portrayal of a blind Colonel, and has received a further seven Oscar nominations during his career.He was presented with the Golden Globes' prestigious Cecil B DeMille career achievement award in 2001.Pacino's latest projects include a big screen reunion with his 'Heat' co-star Robert De Niro and a Salvador Dali biopic.