Lionfish Source: Wayfaring Travel Guide
Puffer fish Source: Fun Gallery
Mushroom Scorpionfish Source: Weird Sea Monsters
Stonefish Source: Wikipedia
Scorpionfish Photo by Nick Hobgood Source: Wikipedia
What do all these fish have in common, besides being freaky? They are all poisonous! The stonefish is the most venomous fish in the world.
Just to end on a good note, here's one weird-looking fish that is NOT venomous.
Barreleye Source: National Geographic