In Slavic mythology, bolotnik (Russian: болотник, pronounced [bɐˈɫotʲnʲɪk]; from boloto, "swamp"), balotnik (Belarusian: балотнiк), bolotyanik (Ukrainian: болотяник) or błotnik (Polish; [ˈbwɔtnik]; "mud" or "puddle")[ is a male swamp spirit.

In Slavic mythology, bolotnik (Russian: болотник, pronounced [bɐˈɫotʲnʲɪk]; from boloto, "swamp"), balotnik (Belarusian: балотнiк), bolotyanik (Ukrainian: болотяник) or błotnik (Polish; [ˈbwɔtnik]; "mud" or "puddle")[ is a male swamp spirit. There are many descriptions of bolotnik. Usually he was portrayed as a man or an old man who has big, frog-like eyes, a green beard and long hair. His body is covered with dirt, algae and fish scales. The legends from the Vitebsk Governorate of Russia said that bolotnik is a dirty, fat, eyeless creature that motionlessly sits at the bottom of the swamp. In some accounts bolotnik is also said to have long arms and a tail