The Sugar Bear originally appeared as a character in the 1964 ABC-TV
Saturday morning cartoon Linus the Lionhearted (1964-1969).

Ad from the above Life magazine

Charles William Post (October 26, 1854 – May 9, 1914)

Post, was a breakfast cereal and foods manufacturer and a pioneer in the
prepared-food industry. After visiting the Battle Creek Sanitarium operated
by John Harvey Kellogg, Post was inspired to start his own cereal company
based on Kellogg’s products. He founded Postum Cereal Co. in 1895. His
first product was Postum cereal beverage and the first breakfast cereal,
Grape Nuts, debuted in 1897. In 1904, C.W. Post followed up the Grape
Nuts label with his own brand of corn flakes, which was initially called
Elijah’s Manna and later renamed Post Toasties in 1908.

1910 ad