While Barr immediately showed remorse for her comments - which she later deleted from Twitter - she didn't immediately apologise, saying: "I was stupid". I am very sorry to have hurt you. Today my words caused hundreds of hardworking people to lose their jobs.
Jarrett appeared on a MBNBC town hall to discuss "everyday racism".
Emmy-winning comedian and Roseanne consulting producer Wanda Sykes was the first prominent figure associated with the show to cut ranks, quitting hours after Barr's comments.
Barr had earlier written that she had done something "unforgiveable" and "indefensible" and asked her followers not to defend her.
She got her start in Hollywood in the early 1990s, developing movie ideas at 20th Century Fox and then becoming a story editor for Steven Seagal's company, which was based at Warner Bros. You know who I blame for this? After an outcry, she said Tuesday that she'll leave Twitter.
The lure of an adoring public who supported her on Twitter must have been too strong.
Barr served as a star and executive producer on the ABC show, which was a ratings phenomenon when it returned to USA television earlier this year for a 10th series, after its original run came to an end in May 1997.
"As I tell my 4-year-old, one makes a choice with one's actions", Rhimes tweeted.
Lemon began the segment by pointing to some of Barr's many controversial statements in the past and suggesting these new comments from her - in which she compared Valerie Jarrett to an ape - are nothing new.
She also fired back at Michael Fishman and Sara Gilbert's statements.
"I think we have to turn it into a teaching moment", Jarrett said. Was it really that savvy for ABC to further enrich and empower a celebrity whose well-documented racist and transphobic beliefs only serve to worsen the pain and vulnerability felt by America's truly marginalized communities?