'Hellboy' (2004)

Creepy features: Back on the big screen in 'Hellboy 2: The Golden Army', the merman-like creature has gills, webbed hands and a frontal lobe resembling that of a dolphin. He has the power of the most mysterious and intelligent underwater creatures enabling him to transmit and receive information psychically.

Friend or foe? Friend! He works faithfully alongside Hellboy as a secret weapon for the Bureau for Paranormal Research and Defence. A useful creature to have around.