Gila Monster is the world only known poisonous lizard.
However the poison level is low.
So Gila monster has to bite and hold, while emitting poisonous saliva. The human victims (mostly drunk) usually lose a limb, but the death is very rare.
I am aware of only one death so far so this would be the second one.
While petting Gila monster is not recommended, you just have to be a real idiot to get killed by Gila monster.
The closely related Mexican Beaded lizard is also poisonous. And new research indicates Komodo Dragons' saliva contains toxin.