Sandra Bullock, widely known as America's Sweetheart, turned 50 on Saturday.

The Oscar-winning actress, who gained fame from her role in the 1994 film Speed, has successfully made viewers laugh and cry over the years with her long list of movie credits. Bullock is also one of the few actors who has truly mastered both comedic and dramatic roles.

In honor of her birthday, below are five of Bullock's most memorable performances.

28 Days (2000)

In the comedic drama, Bullock immaculately played Gwen Cummings, a newspaper columnist forced into rehab for alcoholism.

Miss Congeniality (2000)

Bullock lit up the screen as Gracie Hart in this comedy. The movie was such a success it led to a sequel five years later.

Crash (2004)

Bullock played a cynical wife named Jean Cabot in the film, which won the Academy Award for best picture in 2006. Her character's cold demeanor was so believable throughout the film. Yet, in the end, Bullock was easily able to make viewers feel for her character rather than dislike her.

The Blind Side (2009)

In the 2009 film based on the true story of NFL player Michael Oher, Bullock played the athlete's feisty adoptive mother, Leigh Anne Tuohy. Bullock's heartfelt portrayal earned her the Oscar for best performance by an actress in a leading role in 2010.

Gravity (2013)

You would think seeing one character onscreen for the majority of a movie would become humdrum, but Bullock captivated audiences with her role as Ryan Stone in the Oscar-winning film.

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