The bodyguard, Tom Majercak, told Fox News he didn't have a pleasant experience when he protected her at the 2014 Oscars. DeGeneres was the host of the televised award ceremony.
"I'm holding their hands and walking them through individuals and large groups of people. Ellen is the one person that I've been assigned to – and I've been assigned to quite a few celebrities – that has never taken the time to say hi to me," he told the publication.
DeGeneres' wife was far warmer and welcoming, he says. According to Majercak, the talk show host didn't say "hello" or thank him for his work protecting the star's mother, herself, and her wife.
He called her behaviour "very cold", "sly", and "demeaning".
At the glitzy Governor's Ball after the Oscars' ceremony, the bodyguard says he witnessed more unsettling behaviour from the star, alleging she had pre-approved celebrities who were permitted to come to her table.
Majercak was motivated to come forward with his experience after hearing comments from Dutch beauty blogger Nikkie de Jager.
She appeared on the show after her video where she came out as transgender went viral. She told &C magazine her experience was far less friendly than she expected.
"Maybe I'm being naive, but I expected them to welcome me with confetti: 'Welcome to The Ellen DeGeneres Show!'," she said.
"But instead I got greeted by an angry intern, who was a bit overworked. I expected a Disney show, but I got a Teletubbies after dark."
Majercak says he understands DeGeneres' job as a talk show host is a high-pressure role, but his experience with the host has bugged him for years.
"When you see her on TV, people fall in love with her but it is a false facade and bravado," he told Fox News.
"You start hearing these stories and I was like, 'Man, there's got to be more to this'. She's not the person she portrays to be that she's playing off of society. That's my opinion."
Fox News did not receive a response from DeGeneres' team when it requested comment.