187coyote is correct about all the hoaxes that have been perpetrated or attempted. He's also correct about the Patterson film; debate has waged for years on it's authenticity. It has yet to be "proven" authentic or a hoax. My OPINION is that it is authentic.
I must also suggest that there is much more evidence that these creatures exist than there is evidence that they do not.
Consider this gentlemen: IF they truly exist, you and I benefit much more if they stay in the realm of legend. Why? Imagine what would happen if, while calling coyotes, R Buker shot one in the ear with his .17 Rem and killed it. He packs it back and gets his 15 minutes of fame with Brian Williams on MSNBC News. What would happen next?
Enter the Sierra Club, the Audubon Society, Friends of the Earth, Greenpeace, the National Geographic Society, the Department of the Interior, ad infinum (and every other political group that formerly didn't give a damn about Bigfeet). They would (correctly) point out that these creatures are incredibly unique, and obviously in danger of extinction, since there are clearly not very many of them. They would then be a major focus in every EIS (Environmental Impact Statement) for every new proposed project or activity. Huge areas of the Pacific Northwest, from California to Alaska, would be subjected to new scrutiny to determine what you and I could and COULD NOT DO in those areas.
Get the picture?
My suggestion: if you happen to see a large, furry creature walking around out there on two legs, hold your fire, watch, snap a photo (for pure monetary gain, and for something for the "experts" to debate), and consider yourself lucky. Shooting the beast would likely bring you only legal trouble, and would also bring us all into a political morass that we could never win and would certainly regret.