Lizards (Lacertilia Giganteus) are Slayer monsters found in the Kharidian Desert that require level 22 Slayer to kill. Ice coolers, which can be bought from any slayer master, are required to kill them. The cooler will be consumed, so multiple coolers are necessary for slayer trips.
They can be killed in place of Desert Lizards on a slayer task, and are found within the same area as the desert lizards. They will provide more experience on a task than desert lizards.
They are located in the Kharidian Desert north of Nardah. The fairy ring code DLQ is the best way to reach them - there are some just north-west of the ring. Another way to get to them is to go through the Shantay Pass, head south-east and cross over the first bridges. The lizards should be just south of the crossing. The lower level Small Lizards and Desert Lizards are also found in this location.
Level 77 lizards are also located near the east wall of Sophanem.
Ice coolers must be used on them when they reach 1-20 life points in order to kill them. If an ice cooler is accidentally used when the desert lizard has more than 20 life points, it will still be used up but have no effect. Players would be wise to bring a few extra because of this. Waterskins (and a means of filling them, such as a knife for cutting cacti or Humidify) or an enchanted water tiara should be brought to avoid dying in the desert due to heat. Desert clothing may be useful if you can afford to fight without decent armour. Magic attacks appear to be effective, particularly fire spells, although melee works well enough.
These Lizards should be killed for the most experience, as they have more life points. There are two that spawn due north-east of the fairy ring, almost at the edge of the map. They are each near a cactus. You can kill the first lizard, slash a cactus with knife, move to the second, kill lizard, slash cactus, repeat as needed. They drop big bones, so more experience in slayer, combat, and prayer is gained than with the smaller lizards. On the other hand, killing the smaller lizards allows you to complete your task more quickly.