Автор Миши - Виктор Чижиков, известный иллюстратор детских книг.
A bit of history for English-speaking users: "the Olympic Mishka" is the name of the bear mascot of the 1980 Moscow Olympic Games, designed by children's books illustrator Victor Chizhikov. Misha is the first mascot of a sporting event to achieve large-scale commercial success in merchandise (even in children cartoons), which is now a common practice for other events' mascots.
In Russian, Misha / Mishka is a short form for the Russian male name Mikhail (Michael). This name, in any of its forms, is a common colloquialism in Russian for a bear, because it is similar to the standard name for bear - "медведь" (medved). Also, most anthropomorphic bears in Russian fairy tales have this name.