Oski the Bear (Oski) is the official mascot of the University of California, Berkeley ("Cal"), representing the California Golden Bears. Named after the Oski Yell,^[1] he made his debut at a freshman rally in the Greek Theatre on September 25, 1941.^[2][3] Prior to his debut, live bears were used as Cal mascots.^[4]

Oski's name, design, and character were developed by William “Rocky” Rockwell, who was the first student to play the role, and Warrington Colescott, an editor of The Daily Californian and famed satirist.

Since his debut, Oski's activities have been managed by the Oski Committee, which also appoints a new Oski whenever a replacement is required. Historically, persons who played Oski were male and of short stature (under 5'7"), although the gender requirement was dropped around 1974.^[5]

Oski's identity is protected by the Committee, and wearers of the suit generally do not disclose their identity to the public. One faculty member is aware of the students on the Oski Committee to provide accountability for any incidents.^[1] To that end, there may be multiple members of the Committee who wear the suit, depending on their schedules.^[5]

Oski was suspended for two weeks in January 1990, for throwing a cake towards Oregon State fans, of which some landed on the father of Oregon State point guard Gary Payton.^[6]

In 1999, the Associated Students of the University of California (ASUC) passed a bill calling for a makeover of the "poorly constructed and pathetic version of a bear". The ASUC president vetoed the bill.^[7]