Trout Lake is a lake in the municipalities of East Ferris and North Bay, Nipissing District, Northeastern Ontario, Canada. It lies approximately 6 kilometres (4 mi) east of the much larger Lake Nipissing, with the city of North Bay in between them. Trout Lake is the source of the Mattawa River and a significant body of water on a well-known historic North American voyageur (fur-trading) route. It is about 11 kilometres (7 mi) long and 4 kilometres (2 mi) wide and exits eastward into the Mattawa River, which flows via the Ottawa River to the St. Lawrence River. Some of the most difficult portages are found on this part of the voyageur route between Trout Lake and the end of the Mattawa River, e.g., Portage de Mauvaise Musique, located at the Talon Chute (named after explorer and voyageur Jean Talon).

Due to the short overland distance to Lake Nipissing, Trout Lake became a natural waypoint for Voyageurs en route to and from Mattawa.

A train derailment in the 1980's resulted in a significant toxic spill, which ended up wiping out the lake's population of landlocked Atlantic salmon.

Although Atlantic salmon was successfully introduced into the lake in the past, spawning in Four Mile Creek, they did not survive the 1980's zinc spill. The lake has since been cleaned up and salmon has been re-introduced. The most common fish species today are; lake trout, largemouth bass, and northern pike, though several other species are present.

The City of North Bay (population approx 54,000) draws its drinking water from Trout Lake. While the urban core of North Bay is located primarily between Trout Lake and Lake Nipissing, the city limits contain the lake's entire northern shore. Much of the lake's southern shore is located within the township of East Ferris.

The City of North Bay maintains two lifeguard-staffed swimming beaches on the western shores of the lake.

North Bay Water Aerodrome (CNH7) is a seaplane base located on the north shore of Delaney Bay, on the north-western end of the lake.

• Delaney Bay
• Dugas Bay
• Four Mile Bay
• Milnes Bay
• One Mile Bay

• Camp Island
• Cedar Island
• Dave Island
• Dellview Island
• Dunn Island
• Falconbridge Island
• Fitzsimmons Island
• Hemlock Island
• Hughes Island
• Joe Island
• Little Joe Island
• Louisville Island
• Murdoch Island
• Payne Island
• Poplar Island
• Rolph Island
• Shaftesbury Island
• Sunset Island
• Three Sisters Islands
• Trout Island

• Doran Creek
• Four Mile Creek
• Hogan Creek
• Lees Creek

• List of lakes in Ontario