Joker Venom has similar properties to laughing gas in that it makes its victims laugh uncontrollably, but has a horrific side-effect known as a "Joker Grin" in which the victim's face is distorted into a grotesque death grin similar to the Joker's own disfigured face.
In Batman: The Animated Series, the Joker was prone to utilizing this gas as an alternative to killing. The creators stated that Joker couldn't kill in the series due to it being a children's show, although they felt it was as bad, if not worse.
One of the most notable uses of Joker Venom occurred in the 1989 film Batman, where it is referred to as "Smylex." During the film's climax, the Joker attempts to use Smylex gas, carried in parade balloons, on much of Gotham City's population.
In Batman: Arkham Asylum the toxin is called "Happy Gas" by the Joker and "Joker Toxin" by others. The gas causes the player character to die when exposed to it.
- Laughing Gas
- Joker Gas
- Happy Gas
- Giggle Gas
- Joker Juice
- Laughing Toxin
- Smiley Gas
- The Grinning Death