The Snow Ghost is the titular main antagonist of the Scooby-Doo, Where Are You? episode, "That's Snow Ghost".
He was the costume of Mr. Greenway who wanted to scare people away from his smuggling operation so he dressed up as the Snow Ghost after hearing that Tibetan monk Fu Lan Chi thought that the Yeti's ghost was out to get him.
Greenway took advantage of this wild story and became the ghost of that yeti, the Snow Ghost, who would then scare people away from the abandoned sawmill where Mr. Leech brought and smuggled stolen jewels. Their plan was foiled when Mystery Inc. came to Greenway's lodge, and investigated this mysterious ghost.
The original plan was to pour water all over the Snow Ghost, freezing him solid to enable capture. Unfortunately, the water froze before it could reach him, then the ghost grabbed Scooby and tried to throw him off the cliff. Shaggy then threw a snowball at the Snow Ghost, knocking him over. Whereupon he started to roll downhill creating a giant snowball which engulfed the entire gang, too. The snow ball rolled until it hit a large rock, then, the Snow Ghost's mask fell off, revealing Greenway.
He later appears in The Nintendo 64 version of Scooby-Doo! Classic Creep Capers, where he is the second boss after The Black Knight. The second level is a retelling of the Snow Ghost's episode.
Scooby Doo, Where are You!
The 13 Ghosts of Scooby-Doo
Be Cool, Scooby-Doo!