He was 91. I'm too young to have been aware of him when he was at his peak, particularly with Dean Martin. His telethons collectively earned well over a billion dollars for his cause.
His career took off faster than anyone's I know about. He was twenty years old playing a club in Atlantic City, a singer got sick, he knew Dean and suggested him as a replacement, saying they could do an act together. Dean showed up, they hadn't produced the joint act, the owner went to Lewis and said he expected that promised act immediately. Martin and Lewis batted some ideas around, scribbling them on a pastrami sandwich wrapper. They went on in front of three people. Two hours later they were still at it and those three people were having hysterics. Those people raved about the act, so the next night they had a lot more people. Repeat, with associated exponential increase in audience. Repeat again. And again. It took about a week for them to be booked into the Copacabana in New York, where the exponential expansion didn't stop, to the point where they were soon the hottest act in the country.
Lewis was opinionated and vocal. That often didn't go over well, particularly in his later years when a seriously sexist streak surfaced. But, like the guy or not, he was enormously influential in a whole lot of ways. He was producing, directing, writing, and acting before guys like Woody Allen and Mel Brooks. He needed a way to see what he'd just done on camera quickly so he'd know immediately if he had to reshoot, so he rigged up a video camera In order to check himself out in close to real time. That became standard operating procedure in the entire industry. In slapstick, he preceded guys like Jim Carrey, who said that without Lewis, there was no Carrey, and Robin Williams, whose manic style wasn't as manic as Lewis'. People don't think of the man as outrageous today but when he was working with Martin that was a very different story. He was highly unpredictable and over the top. People on shows they guested on weren't safe and, physically, neither was he. He spent a lot of his life on pain meds from falls he'd taken to get laughs.
Lewis knew what he was doing, in detail. Those inside the industry tend to respect him most. We just lost an extremely important man in show business history.