Crotalus scutulatus Mohave Rattlesnake
As I write this, the English name for this species is spelled "Mohave" by the SSAR names list that I'm using. But there's a strong argument being made by some herpetologists that "Mojave" is the more appropriate spelling, and a lot of references use that spelling.
Subspecies I've seen:
C. s. scutulatus
Northern Mohave Rattlesnake
Crotalus scutulatus scutulatus Northern Mohave Rattlesnake
near California City, Kern County, CaliforniaMay 19, 2001
Northern Mohave Rattlesnake (Crotalus scutulatus scutulatus)
Mohave rattlesnakes have a reputation for having especially potent venom and being especially aggressive. Studies have shown that the venom is quite variable among different populations of this species. The aggressive reputation is probably mostly or entirely legend. (People tend to assume that dangerous animals are aggressive, whereas in truth most of them are shy and want nothing more than to avoid contact with humans.)

My friend Don MacCubbin and I saw this one on a road at night. We encouraged it off the road with my tripod's extended legs so it wouldn't get squashed. It sluggishly moved in the direction we suggested, but didn't show a trace of aggressiveness.

One distinguishing identification mark of this species is seen clearly in this photo. The tail near the rattle is banded black and white, with the white bands are much thicker than the black bands.

Sierra Vista, Cochise County, ArizonaAugust 7, 2004
Northern Mohave Rattlesnake (Crotalus scutulatus scutulatus)
I spotted this rattlesnake as it was prowling near the side of a little-used road at night. It seems to be trying to hide behind a blade of grass.
Cochise County, ArizonaAugust 16, 2013
Northern Mohave Rattlesnake (Crotalus scutulatus scutulatus)
Gathering the last warmth of the sun by stretching out across a dirt road near dusk.
Cochise County, ArizonaAugust 22, 2016
Northern Mohave Rattlesnake (Crotalus scutulatus scutulatus)
Fall is baby rattlesnake season in southeast Arizona, and this was the first of many baby rattlesnakes I found over the next few nights.
near Animas, Hidalgo County, New MexicoAugust 22, 2016
Northern Mohave Rattlesnake (Crotalus scutulatus scutulatus)
Not all of the rattlesnakes out at night in the fall are babies, though. This is a hefty adult.
Cochise County, ArizonaAugust 23, 2016
Northern Mohave Rattlesnake (Crotalus scutulatus scutulatus) Northern Mohave Rattlesnake (Crotalus scutulatus scutulatus)
Just a couple of the five or six babies I saw on the road this night.
Cochise County, ArizonaAugust 24, 2016
Northern Mohave Rattlesnake (Crotalus scutulatus scutulatus) Northern Mohave Rattlesnake (Crotalus scutulatus scutulatus)
And a couple more from the next night.
near Animas, Hidalgo County, New MexicoAugust 24, 2016
Northern Mohave Rattlesnake (Crotalus scutulatus scutulatus)
This one is interesting. The large scales, relatively thick light tail bands, and (only partially visible) light stripe behind the eye all point to C. scutulatus. But the multiple small scales between the supraoculars, and the tail-most tail band being black are generally characteristics of C. atrox. It is possible I suppose that it is a hybrid, but I think it's much more likely that it's a somewhat aberrant C. scutulatus. Several people have told me that they agree with this ID.
Printed references: