What genus includes the Gila monster and Mexican beaded lizards?

The genus that includes the Gila monster and Mexican beaded lizards is Heloderma.

Heloderma is the only living genus in the lizard family Helodermatidae. It contains the Gila monster, Heloderma suspectum, and four species of beaded lizards, including the Mexican beaded lizard, Heloderma horridum. All living members are venomous and have distinctive bead-like scales strengthened by bony osteoderms.

Unlike snakes, Heloderma lizards have venom glands in the lower jaw rather than behind the eyes. Their venom is delivered through grooved teeth, with chewing helping move venom into a wound. Their tails also store fat, an important adaptation for surviving seasonal shortages in their generally dry or seasonal habitats.

The genus name means studded skin, referring to the osteoderm-reinforced scales. Another classification trap is Varanus: monitor lizards may look similar and are distant relatives, but Gila monsters and beaded lizards belong to their own family. In 2013, four former beaded-lizard subspecies were elevated to full species.