Randi is a debunker, in the same mold as Houdini was a debunker of mediums in the 1920's. A magician that exposes frauds that use magic tricks to promote so called psychic powers to bilk people out of money etc. He is not a formal scientist, but he is useful in that he has exposed many frauds and quacks. He is associated with an organization called CSICOP that publishes
The Skeptical Inquirer. A useful magazine, if not very well known.
They have a website:
CSICOP
-Zeno