Katharine Hepburn won four awards, all for Best Actress.

Best Actress in a Leading Role

Morning Glory (1933)

Best Actress in a Leading Role

Guess Who's Coming to Dinner (1967)

Katharine Hepburn was not present at the awards ceremony. George Cukor accepted the award on her behalf.

Best Actress in a Leading Role

The Lion in Winter (1968)

Tied with Barbra Streisand for Funny Girl (1968). Hepburn became the third performer to win consecutive awards, and the first to win three awards for lead roles. Anthony Harvey, the film's director, accepted the award on her behalf.

Best Actress in a Leading Role

On Golden Pond (1981)

Katharine Hepburn was not present at the awards ceremony. Presenter Jon Voight accepted the award on her behalf.

More Info: en.wikipedia.org