Elk are the most abundant large mammal found in Yellowstone and are an important species within the Greater Yellowstone Ecosystem. Yellowstone provides summer range for an estimated 10,000–20,000 elk (Cervus canadensis) from six to seven herds, most of which winter at lower elevations outside the park.

As of early 2026, the elk population in Yellowstone National Park is estimated to be between 10,000 and 20,000 individuals across several distinct herds, making them the most abundant large mammal in the park. The largest and most famous of these is the Northern Yellowstone Elk Herd, which migrates between the park's northern range and areas in Montana. Recent counts of this specific herd have hovered around 5,000 to 6,000 animals, which is slightly above the management objective of 3,000 to 5,000. The population is carefully monitored by biologists using GPS collars to understand how the "full suite" of predators—including wolves, grizzly bears, and mountain lions—impacts their survival. While the numbers are lower than the peak of 19,000 seen in the mid-1990s (prior to wolf reintroduction), the current population is considered ecologically stable and more in balance with the available vegetation. Visitors are most likely to see these majestic animals in the Lamar and Hayden Valleys, or famously wandering through the historic Mammoth Hot Springs area, where they often lounge on the lawns of the park's headquarters.