An excerpt from Wikipedia:
Its name (never mentioned in the commercials) is Sascha, after the wife of the founder of the company. Theodore Hamm's wife was named Louise. The Hamm's Beer bear was created by Patrick DesJarlait, an Ojibwa, in 1952 for an advertising campaign produced by the Campbell-Mithun advertising agency. For a period, a real bear named Sascha trained by Earl Hammond appeared in commercials as well. The Hamm's Beer bear was featured on endless array of signs, glassware, and tchotchkes such as clocks, ceramic miniatures, and ashtrays. It was so well-known and identified with Minnesota that the St. Paul Pioneer Press named the bear as a runner-up on its list of "150 Influential Minnesotans of the Past 150 Years" in 2000.
There's also the YouTube videos and the Onion Radio News: Hamm's Beer Bear Found Dead In Flop Zoo. I used to see the Hamm's bear all the time when I was a kid watching the Chicago Cubs on WGN-TV.