Ogopogo is the name given to a lake monster reported to live in Lake Okanagan, British Columbia, Canada.

The Ogopogo, known under the Salish name of N'ha·a·itk, or Naitaka, has existed in local myth for an unknown period of time and pre-dates western settlement of the area, as do native references to the "Great-beast-in-the-lake" and the "Snake-in-the-lake" and Petroglyphs, or pictographs found near the headwaters of Powers Creek, showing a serpent-like beast, which may represent the earliest evidence of legend's existence.

Tribes in Okanagan were always wary of traveling across the lake and often carried animals that could be sacrificed in the event that the creature was sighted, and it was documented in the history of Okanagan Mission that none of the local populace were willing to fish near Squally Point, where they believed the entrance to Ogopogo's cave was located.

The first documented sightings of the Ogopogo by European settlers date back as far as 1860 and occur as the area was being colonized, though the first clear sighting, witnessed by a large group of people, occurred in 1926 at an Okanagan Mission Beach. There were about thirty cars of people who all claimed to have witnessed the same event. It was also in this year that Bobby Carter, then editor of the Vancouver Sun, wrote, "Too many reputable people have seen [the monster] to ignore the seriousness of actual facts."The first film of the alleged creature is The Folden Film, filmed in 1968 by Art Folden, which shows a dark object propelling itself through shallow water near the shore . The film was shot from on a hill above the shore. The film was once enhanced, and showed a solid "reptilian" 3D object.

Ogopogo was filmed again in 1989 by Ken Chaplin. Ken was with his father Clem Chaplin, talking about where he saw the Ogopogo, when suddenly both of them saw a snake-like animal swimming the lake. The animal was seen turning and even flicked its tail to create a splash. Some believe that the animal the Chaplins saw was simply a beaver, because the tail splashing is a well-known characteristic of beavers. However, Ken claims he saw the animal slap its tail while its head was clearly visible above the water, while a beaver's head would be either be level to the water or already diving prior to a tail slap. Also, Ken alleges the animal he saw was 15 feet long, far larger than a typical beaver (beavers are approximately 4 feet long). A few weeks later, Ken came back with his father and his daughter and filmed it again

British zoologist Dr. Karl Shuker has categorized it as a 'many hump' variety of lake monster, and suggested it may be a kind of primitive serpentine whale such as Basilosaurus. Other sightings have also indicated that the Lake Okanagan beast is a 'many hump' rather than the 'long neck' type.However, because the physical evidence for the beast is limited to unclear photographs and film, it has also been suggested that the sightings were really of otters and logs . Another theory is that the Ogopogo is a lake sturgeon. There is a spot however with a clear view to the island where they say the entrance to his cave is, but it was recently demolished and made way for a new housing development

In 1990, a Canadian postage stamp depicting an artist's conception of the Ogopogo was issued. Ogopogo was an enemy in Square's Super Nintendo game Final Fantasy IV.
Ogopogo was both codename and mascot for 1996's Microsoft Publisher 97, with Ogopogo graphics featured prominently in the beta setup.