Muddus National Park, National park in Norrbotten County, Sweden.

Muddus National Park covers 49,340 hectares in Gällivare and Jokkmokk municipalities, southwest of Gällivare town. It is Sweden's largest forest national park, with old-growth pine forest, mottled bog and marshland, and deep ravines. The Muddusjokk waterfall drops 42 metres about 10 km north of the southern entrance, and the Moskoskoru ravine reaches 100 metres deep.

Muddus was made a national park in 1942 to protect its old pine forest and mire landscape, and it was enlarged in 1984 to 49,340 hectares. It lies in Swedish Lapland, mostly in Gällivare Municipality with the rest in Jokkmokk, and forms part of the Laponia World Heritage Area. It is Sweden's largest forest national park.

The park lies in Sápmi, the Sami homeland, and its Sami name is Muttos, of which Muddus is the Swedish spelling. The area is tied to many stories of Sami history and mythology. Reindeer graze in the lower parts of the park, and the forests also hold lynx, bear, marten and weasel.

The park has marked hiking trails of different lengths and difficulty, so visitors can choose a route that fits their pace. Basic shelters are available at points along the trails, making an overnight stay in the forest a practical option.

A pine tree growing inside the park is over 700 years old, placing it among the oldest trees of its kind in Europe. It was already standing long before the park was created, having survived fires, frost, and centuries of change on its own.