Well, we have "Champ" the Lake Champlain monster. He is basically Americas equivalent of the Loch-Ness Monster. Among the numberous Champ related events include an appearance on the TV shows
Unsolved Mysteries,
Sightings, and
The Today Show, a Discovery Channel special in 2003, and resolutions by the Vermont House and the New York Assembly and Senate declaring that Champ is protected.
Champ's Home Page