"Blue Whale" (Russian: Синий кит, romanized: Siniy kit), also known as the "Blue Whale Challenge", is a social network phenomenon dating from 2016 that is claimed to exist in several countries. It is a "game" reportedly consisting of a series of tasks assigned to players by administrators over a 50-day period, initially innocuous before introducing elements of self-harm and the final challenge requiring the player to commit suicide.

"Blue Whale" first attracted news coverage in May 2016 in an article in Russian newspaper Novaya Gazeta that linked many unrelated child suicides to membership of group "F57" on the Russian-based VK social network. A wave of moral panic swept Russia.However, the piece was later criticised for attempting to make a causal link where none existed, and none of the suicides were found to be a result of the group activities.Claims of suicides connected to the game have been reported worldwide, but none have been confirmed.