Meryl Streep, Cate Blanchett, Ethan Hawke, Amy Adams, Ellen Burstyn and Spike Lee were among the famous mourners at the private funeral for Philip Seymour Hoffman in Manhattan.
The list of guests also included Michelle Williams, Julianne Moore, Joaquin Phoenix, Louis CK, Mary Louise Parker, John Slattery, Jerry Stiller, Marisa Tomei, Diane Sawyer and her director husband, Mike Nichols.
Hoffman, 46, was found dead on February 2 of an apparent heroin overdose in his apartment. He leaves behind his partner of 15 years, Mimi O'Donnell, and their three children.
The actor's body was carried into the church by pallbearers and O'Donnell - holding their youngest child - followed. Playwright David Bar Katz, who found Hoffman's body, looked visibly upset as he arrived.
The ceremony was being held at the Church of St Ignatius Loyola, the same limestone church that hosted the funerals of Jacqueline Kennedy Onassis, Lena Horne and Aaliyah.
A larger memorial service is being planned for later this month. Family and close friends have previously gathered for a private wake at the Frank E Campbell Funeral Home in Manhattan.
The actor was nominated for Academy Awards four times - for Capote, The Master, Doubt and Charlie Wilson's War. He also received three Tony nominations for his work on Broadway, which included an acclaimed turn in 2012 as the weary and defeated Willy Loman in Death Of A Salesman.
The theatre community mourned the actor with a candlelit vigil outside his beloved LAByrinth Theatre Company and with Broadway's marquee lights turned off for a minute.
More tests are needed to determine what exactly killed Hoffman, who was found with a syringe in his arm and what authorities said were dozens of packets of heroin in his apartment. Autopsy results were inconclusive, authorities said this week.
Hoffman spoke candidly over the years about past struggles with drug addiction. After 23 years sober, the versatile actor reportedly checked himself into rehab for 10 days after relapsing in 2012.
Three people have been arraigned on drug charges in connection with Hoffman's death, including one who is facing a felony charge of heroin possession with intent to sell. Lawyers for the three people charged vigorously denied their clients had any role in Hoffman's death.
Most of those who attended the funeral had personal ties to Hoffman. He and Cate Blanchett co-starred in The Talented Mr Ripley, and Hoffman starred in Spike Lee's The 25th Hour. Ellen Burstyn and Hoffman were in Red Dragon, and Ethan Hawke co-starred with him in Before The Devil Knows You're Dead.
John Slattery directed Hoffman in his new film God's Pocket while Joaquin Phoenix shared the screen with Hoffman in The Master.