Ded Moroz (Russian: Дед Мороз, [dʲɛt mɐˈros]; Russian diminutive: Дедушка Мороз, Dedushka Moroz; Slovak: Dedo Mráz; Polish: Dziadek Mróz; Belarusian: Дзед Мароз, Dzied Maroz; Ukrainian: Дід Мороз, Did Moroz) or Morozko (Russian: Морозко) is a legendary figure similar to Saint Nicholas, Father Christmas, and Santa Claus who has his roots in Slavic mythology. The tradition of Ded Moroz is mostly spread in East Slavic countries and is an important part of Russian culture. At the beginning of the Soviet era, communist authorities banned Ded Moroz. Nevertheless, he soon became an important part of the Soviet culture. The literal translation of Ded Moroz is Grandfather Frost.

Ded Moroz wears a heel-length fur coat, in red or blue, a semi-round fur hat, and valenki on his feet. He has a long white beard. He walks with a long magic stick and often rides a troika. He is often depicted bringing presents to well-mannered children, often delivering them in person in the days of December and secretly under the New Year Tree over night on New Year's Eve.

The residence of Ded Moroz in Russia is considered to be the town of Veliky Ustyug, Vologda Oblast. The residence of the Belarusian Dzyed Maroz is said to be in Belavezhskaya Pushcha.

In East Slavic cultures, Ded Moroz is accompanied by Snegurochka (Russian: Снегурочка, Snegurochka; Belarusian: Снягурка, Sniahurka; Ukrainian: Снігуронька, Snihurońka; "Snow Maiden"), his granddaughter and helper, who also wears long silver-blue robes and a furry cap or a snowflake-like crown. She is a unique attribute of Ded Moroz, since similar characters in other cultures do not have a female companion.