I had never actually heard of Johnny Moss until recently. Bluff Magazine has an article naming him the #6 on the 40 Greatest Champions. Here's a little bit from the article written by Paul Oresteen, that I thought was amazing:
Moss had grown up with Benny Binion in Texas and the two were life long friends. In 1949 the world’s most famous gambler, Nick “The Greek” Dandalos, arrived at Binion’s Horseshoe Casino looking to play high stakes heads up poker. Binion immediately knew that Johnny Moss was the man to play him. In what would become poker’s most famous game, the precursor to the WSOP, Nick the Greek and Moss would play a five month long heads up match.
Binion, a master of publicity, put them in front of the casino to attract tourists and gamblers alike. No official records were kept but it’s guessed that Moss beat the Greek out of four million dollars before an exhausted Dandalos rose from the table and spoke poker’s most famous quote, “Mr. Moss, I have to let you go.”
They played heads up, for five months, and the Greek lost four million dollars in 1949. That's the equivalent of about $30 million if they played today.