Philip Seymour Hoffman Wake: Cate Blanchett, Amy Adams, Michelle Williams Mourn the Actor

Cate Blanchett, Joaquin Phoenix, Amy Adams and Michelle Williams were among the friends and family who gathered on Thursday to remember Philip Seymour Hoffman at a private wake.

Also in attendance were Diane Sawyer, Ellen Burstyn, J. Edgar co-star Josh Hamilton, Hoffman's mother, Marilyn O'Connor, his longtime partner Mimi O'Donnell and three children Cooper Hoffman, Willa Hoffman and Tallulah Hoffman, according to the Associated Press.

The memorial was held at the Frank E. Campbell Funeral Chapel on Manhattan's Upper East Side -- which has also hosted services for Jacqueline Kennedy Onassis and James Cagney -- and police escorted guests in and out of the building.

STORY: Philip Seymour Hoffman Dead at 46

Many of the A-list attendees have starred alongside the iconic actor, with Adams appearing with him in Doubt and The Master.

The 2008 death of Williams' former partner, Heath Ledger, has been compared to that of Hoffman's, who died of a suspected drug overdose on Sunday at 46.

STORY: Philip Seymour Hoffman Autopsy Results Inconclusive

Police found Hoffman dead on the floor of the bathroom in his West Village apartment with a needle sticking out of his left arm. According to reports, close to 50 envelopes of heroin were found in Hoffman's apartment, as were several used and unused syringes and prescription drugs, the NYPD told The Hollywood Reporter on Monday.

Hoffman's autopsy results were inconclusive, the New York City medical examiner's office told THR Wednesday. Additional tests, including a toxicology study, will need to be done in order to determine the actor's cause and manner of death. Those tests could take anywhere from a few days to a few weeks.