While Ivan Sanderson was not the first man to chase after cryptids, he was the man who named the field that we all dabble in.

He and fellow zoologist Bernard Heuvelmans defined the actions of scattered peoples in the 1950s, gathering the idea into a name: Cryptozoology - the study of hidden animals. This concept encompasses both the "folklore creatures" such as sasquatch and the Loch Ness Monster, and the animals considered extinct and perhaps also folklore.  The term 'cryptid' is said to have been coined by J. E. Wall in 1983, meaning a living thing having the quality of being hidden or unknown.