The largest hummingbird in the world is the South American Giant Hummingbird (Patagona gigas). As mentioned in What is the smallest bird in the world, the Bee Hummingbird, at .06 ounces, is dwarfed by the Giant Hummingbird which weighs in at an astounding 20 ounces.
Giant Hummingbirds have relatively dull plumage compared to many other varieties but still sports the characteristically long beak to access nectar in the trumpet-like blossoms of its favorite energy sources.
Giant Hummingbirds are native to the western South America and in the Andes, specifically, ranging from Ecuador to as far south as northwestern Argentina. For video of this amazing bird, visit the Internet Bird Collection (IBC).