Yep, we called him "Dedek Mraz" in the balkans which also literaly translates into Grandfather Frost.
(Although we did celebrate christmas since the anti-religion clampdown wasn't that aggressive in Yugoslavia.)
Mraz, sounds like мразь, not a very good word :))
Close languages often sound funny to reach other.
The word literally means "something that causes chills" so it's not that different from slavic "mraz". It just had been used exclusively in a figurative meaning to describe something that is so disgusting that it makes one shake.
"дядо мраз" in bulgaria. we also celebrated xmas with a quiet family vegetarian dinner, not having such a massive clampdown on religion, and "mraz" delivered presents on new year's. after 1989 things came back to normality and he's now called "дядо коледа". new year's is just a drinking holiday :)