The Academy of Motion Picture Arts and Sciences gave space requirements as the reason Joan Rivers, Elaine Stritch, Richard Kiel and other recently deceased stars were not included in Sunday's annual Oscars memorial segment.

"Joan Rivers is among the many worthy artists and filmmakers we were unfortunately unable to feature in the In Memoriam segment of this year's Oscar show," an Academy representative said in a statement to Newsday on Monday. "She is, however, included in our In Memoriam gallery on Oscar.com."

Many fans, peers and commentators expressed disappointment on social media that Rivers went unacknowledged.

Actor Michael Chiklis tweeted, "Joan Rivers a glaring omission from the in memoriam segment," and singer Lance Bass asked, "Why was Joan Rivers cut out of the Oscars? Oversight or beef?" Wrote cultural critic Matt Zoller Seitz, "Joan Rivers should've been in the in memoriam segment. She had as much claim to be in there as many people who were included."

Most noted that Rivers -- best-known as a standup comic but who wrote and directed the 1978 Billy Crystal film "Rabbit Test" and appeared in or provided voices for films including "Spaceballs" (1987), "The Muppets Take Manhattan" (1984), "Shrek 2" (2004) and "Iron Man 3" (2013) -- was a longtime staple of Oscar coverage with her red-carpet interviews for E! alongside daughter Melissa.

Melissa Rivers' spokeswoman had no comment.

Broadway star Stritch, Bond villain Kiel and comedians Jan Hooks and Taylor Negron were also among those excluded. Although filmmaker Harold Ramis died in 2014, he was included in last year's tribute.