There are numerous connections to Canada and Canadians in U.S. variety
shows. For instance, Saturday Night Live founder Lorne Michaels is
Canadian. The producer of the Smothers Brothers and Sonny and Cher was
Canadian. And Ed Sullivan's most frequent guests were Wayne and
Shuster, two Canadian comedians.

I'm looking for three other examples of how Canadians have played a
significant part in American variety shows.

Also need links to audio or video clips of such shows.