Michele has found herself at the centre of bullying accusations during her time on the popular musical show, with season six actress Samantha Marie Ware claiming over the weekend that Michele had made her first TV role "a living hell".
Now Willam, who competed on season four of Drag Race and is also an established actor, has added his voice to those accusing her of bad behaviour.
In a Twitter post, he wrote: "Lea treated me so subhuman i left the set of Glee. Pass the [popcorn emoji]"
Willam had been due to appear in the infamous 'Let's Have A Kiki' scene in season four of the show in 2012, even announcing his casting on Twitter, but an appearance in the episode failed to materialise.
Michele has yet to comment on the allegations, although she has already lost a sponsorship deal with HelloFresh as a result of the reports.