The Grizzly Giant is a massive giant sequoia located in Mariposa Grove within Yosemite National Park. Famous for its impressive size and age, the Grizzly Giant has been a symbol of the park since tourism began. The Grizzly Giant stands out with its enormous trunk, which is much larger than typical giant sequoias, and its unique, uneven branches shaped by centuries of weather and environmental factors. Its name comes from its imposing presence, reminiscent of a California grizzly bear.

The Grizzly Giant is the oldest tree in Mariposa Grove, which is Yosemite National Park's largest grove of giant sequoias, containing hundreds of mature trees. Although once considered the oldest and largest tree in the world, recent dating techniques have estimated the Grizzly Giant’s age at about 2,995 years, with a margin of error of plus or minus 250 years. In 1990, the tree's volume was measured at 34,005 cubic feet (962.9 m³), making it the 26th-largest living giant sequoia.

Nineteenth-century photographs and paintings of the Grizzly Giant vividly showcased the immense scale and beauty of giant sequoias, convincing a skeptical public of their existence and spurring early conservation efforts that ultimately protected Mariposa Grove.

On July 16, 2022, the Washburn Fire threatened Grizzly Giant and other trees in Mariposa Grove. The National Park Service used sprinklers to protect the famous tree.