Eight of the world's ten highest peaks are found in Nepal. The country contains or shares Everest, Kangchenjunga, Lhotse, Makalu, Cho Oyu, Dhaulagiri, Manaslu, and Annapurna I—the first, third through eighth, and tenth-highest mountains by elevation.
The two exceptions are K2 and Nanga Parbat, both associated with Pakistan. Several of Nepal's highest peaks sit directly along the Nepal–China border, so “found in Nepal” includes mountains shared across an international boundary rather than only peaks entirely inside Nepal.
All ten belong to the Himalaya or the adjoining Karakoram system and rise above 8,000 metres. Mount Everest, at 8,848.86 metres, is the highest. Annapurna I, ranked tenth at 8,091 metres, is also in Nepal and is famous for the difficulty and danger of its climbing routes.
A common mix-up is the claim that Nepal contains eight of the world’s fourteen eight-thousanders. That statement is also true, but it is a different count from this question, which focuses only on the top ten highest peaks.