A Harlequin or Rillietann, is a member of a very distinct sub-group of the Aeldari species in the Warhammer 40k Universe. They serve the enigmatic Aeldari deity called the Laughing God.
The Harlequins see no distinction between art and war. The Laughing God is the only authority that the Harlequins recognise, and their every deed is thought to be in furtherance of his own inscrutable agenda.
These enigmatic warriors are often credited with supernatural powers, and many amongst both Asuryani and Drukhari society believe that the Harlequins know most, if not all, of the secret paths through the endless maze of the Webway.