The Winter Warlock, later called Winter for short, is a character from the Rankin/Bass Christmas special Santa Claus is Comin' to Town. He is introduced as a mean and despicable creature who is unwilling to let anyone pass across the Mountain of the Whispering Wind and go into Sombertown or vice versa to Rainbow River Valley. Kris Kringle, along with his penguin friend Topper, briefly encounters the Warlock early on during his first trip across the mountain to Sombertown; although Kris manages to escape, the Warlock vows to get him on his return trip.
Winter provides Kris with a magic snowglobe.
Sure enough, when Kris makes his way back after being chased out of Sombertown by Burgermeister Meisterburger and his henchmen, he and Topper are captured by two of the Warlock's tree minions and brought to the Warlock himself. But when Kris gives the Winter Warlock a toy train, the evil in his heart melts away, resulting in him taking on a more human-like appearance and turning good. Winter then becomes a vital friend to Kris, giving him land on the Mountain of the Whispering Wind where he and the Kringles can build a new workshop which to build his toys from and make deliveries to Sombertown easier.
As time goes on, though, Winter starts to lose his powers, to the point where he is unable to successfully do card tricks. This comes at the worst possible time; when Kris is arrested for smuggling toys into Sombertown by the hateful Burgermeister, Winter is unable to defend his friends when he, Topper, and the other Kringles are also arrested by the Burgermeister's trusted lieutenant Grimsley. Winter secretly speaks to Jessica when she comes to his cell, and together they come up with a plan to escape: They use Winter's last magical tool, his Magic Feed Corn, to make Kris' reindeer friends fly, allowing them to help the group escape from the prison.
Later, Winter uses one last bit of magic to create the very first Christmas trees at Kris and Jessica's wedding. By the end of the special, Winter's powers appear to have returned, and he declares that there will indeed be a white Christmas when Kris, now calling himself Santa Claus, makes his annual journey.
Strangely, in Rudolph and Frosty's Christmas in July, Winter is not seen in any of the flashbacks depicting scenes from Santa Claus is Comin' to Town, nor even mentioned in the movie despite his Magic Feed Corn being present in the story. It is unknown why this is the case, but possibly, Winter's similarities to the movie's overall villain, Winterbolt, likely would have necessitated a time-constrained explanation as to why the two characters were different.