Eisenberg, who became famous in the spin-off, had been battling health issues ... he received 2 kidney transplants. He was born with one kidney, which failed and he went on dialysis at age 14. He underwent his first transplant when he was 17 and another when he was 46. His kidney issues stunted his growth -- he was 5' tall.

He was also featured in the TV movie, "Amityville: The Evil Escapes" and "The Horror Show," "Beverly Hills Brats" and "Playroom." In all, he has over 30 credits.

Although Eisenberg was known for "Star Trek: Deep Space Nine," he was also featured in "Star Trek: Renegades" as well as "Star Trek: Voyager." He was also involved in the Star Trek video game back in 2010.

His widow, Malissa Longo, posted, "We didn't officially announce that we had eloped on December 28th, 2018. We were hoping to have a big shindig in celebration of our nuptials, but had to wait to save up the money."

She went on ... "There will never be another light like Aron's. The beauty that he was and the legacy he leaves behind is beyond words. I love him dearly and will miss him eternally. At the moment I'm not sure how to do life without him."

Aron was 50.