In one post, O'Donnell called out the 75-year-old former talk show host for his treatment of season eight competitor Tracey Yukich when she made an appearance on "The Tonight Show with Jay Leno" in 2009. JILLIAN MICHAELS SLAMS 'BIGGEST LOSER' DOCUMENTARY, PUTS CO-STAR BOB HARPER ON BLAST FOR FRIENDSHIP DEMISE

In an Aug. 19 Instagram post, she called out fellow TV icon Jay Leno for a mean-spirited 2009 segment from "The Tonight Show with Jay Leno," which was revisited in the new Netflix docuseries " Fit for TV: The Reality of the Biggest Loser ."

Rosie O’Donnell is taking aim at Jay Leno after one of his cruel late night stunts resurfaced in the new “The Biggest Loser” documentary. The Netflix series, “Fit for TV: The Reality of the Biggest Loser,” shows a clip of Leno reading aloud death threats aimed at former contestant Tracey Yukich while she sits alongside him.