Oliver Tree's Memorial Will Have Celeb Speakers, Multiple Caskets for Characters

Oliver Tree's celebration of life is set to be a star-studded event, with A-list attendees, live performances and multiple caskets ... TMZ has learned.

We've obtained a copy of the flier for the event, which promises to be "a night to remember" ... featuring different caskets for each of his characters, unreleased video content, tribute videos, and live musical performances.

Logan Paul, Diplo, Ethan Klein, Aaron Mercury and more of Oliver's friends and family will serve as guest speakers during the memorial service.

They'll be taking the stage at the UCSC Quarry Amphitheater in Santa Cruz, CA on Saturday to remember Oliver's life and legacy. It will be live streamed on his Twitch and Youtube accounts at 7:30 P.M. PST.

The artist's team launched Dr. Oliver Tree's Extremely Epic Art Grant for Baby Geniuses foundation after his tragic passing last month ... and the family is asking that any donations be made out to the organization.

As you know, Oliver and 5 other people were killed in Rio de Janeiro, Brazil on June 14, when two helicopters collided.

Oliver was 32.