'He-Man' Creator Roger Sweet Dead at 91

Roger Sweet -- the toy designer who created the He-Man character in the "He-Man and the Masters of the Universe" 1980s animated kids' show -- has died at age 91 after battling dementia.

His wife, Marlene, tells TMZ Roger passed away peacefully at his care facility Tuesday morning … just months after she revealed his devastating health decline and launched a GoFundMe to help cover his staggering memory care costs.

As we previously reported ... Marlene said Roger suffered a frightening fall while out walking alone and couldn't remember what happened. Doctors later discovered two brain bleeds ... and he was hospitalized in the ICU before being moved into a memory care facility that cost more than $10,000 a month.

The heartbreaking fundraiser sparked an outpouring of support from fans who grew up on "He-Man and the Masters of the Universe" ... with donations soaring past its original $50K goal and eventually reaching nearly $94K. The Mattel Foundation kicked in $5,000 to help the man whose creations helped define an entire generation of toys.

Roger worked for Mattel in the '70s and '80s and is widely credited with developing He-Man after pitching multiple muscular action figure concepts that eventually evolved into the sword-wielding hero.

His death comes as a new live-action "Masters of the Universe" movie from Amazon MGM Studios and Mattel is set to hit theaters this summer ... proving his creation still has the power of Grayskull decades later.

Marlene tells us that she has been trying to reach the producers of the upcoming movie in hopes that they would dedicate the movie to Roger.

Roger leaves behind a legacy that'll live on every time someone says ... "I have the power!"

Roger was 91.