For years she has used her hit US daytime talk show to promote values of kindness and compassion.
But now, Ellen DeGeneres, one of Hollywood's most prominent liberal voices, has been forced to apologise after accusations of a "toxic" behind-the-scenes working culture.
It follows allegations made by dozens of former employees, to BuzzFeed News, of sexual misconduct, bullying and racism among production staff.
Several showbusiness figures later added to the criticism.
Actor Brad Garrett, 60, who was a guest on the show six times, said: "Sorry but it comes from the top. Know more than one who were treated horribly. Common knowledge."
Lea Thompson, 59, who starred in Back to the Future, added on Twitter: "True story. It is."
DeGeneres, 62, apologised in an email to staff.
She said: "On day one of our show, I told everyone in our first meeting that 'The Ellen DeGeneres Show' would be a place of happiness - no one would ever raise their voice, and everyone would be treated with respect.
"Obviously, something changed, and I am disappointed to learn that this has not been the case. And for that, I am sorry. Anyone who knows me knows it's the opposite of what I believe and what I hoped for our show."
She added: "I relied on others to do their jobs as they knew I'd want them done. Clearly some didn't."
An internal investigation was carried out by Warner Bros. Television, which distributes the programme.
In a statement Warner Bros said it interviewed dozens of current and former employees and was "disappointed that the primary findings of the investigation indicated some deficiencies related to the show’s day-to-day management."
It said there would be staffing changes and it "takes the recent allegations around the show's workplace culture very seriously."