Heloderma suspectum cinctum
The Gila monster is a venomous lizard native to the southwestern US and northwestern Mexico.
This one was spotted at the end of a five day backpacking trip in Saguaro NP. The photos were taken with my old Sony DSC-10 (Point and Shoot) before I got my better camera gear. It was fairly calm until I got a little closer, then it puffed its body up and hissed to look big and tough.