The Monster is an elevated pickup truck, and is available on Grand Theft Auto: San Andreas. It is large, along with huge wheels, and comes standard with an American Patriot style paintjob.
It is available in many places about halfway in the game. The most notable location is at the stadium after completion of the 8-Track in Los Santos. This will automatically spawn a Monster in the parking lot. The monster will also spawn in the caravan park on the second island just as you go out of Richman, which has different paint job.
The Monster's handling is among the best on San Andreas. This is because it has four-wheel steering which is activated when the handbrake button is held. This is a great advantage when trying to complete a sharp turn with such a large vehicle. Of course, the Monster has great off-road ability, but its bouncy suspension is capable of throwing it off the road occasionally. However, it is easy to get back on track again.
There are at least 3 variants of the Monster: a standard Monster (seen in the screenshot above), a Monster based on the Yosemite chassis and sporting a spoiler and roof lights (this can be acquired by dating Michelle in San Fierro) and a Monster with no paintjob.
The Monster can be imported once five cars from list one are delivered to the crane, for $32,000 on Wednesdays.