Giraffatitan (meaning "titanic giraffe") is a genus dinosaur that lived during the late Jurassic Period. Giraffatitan was for many decades known as the largest dinosaur but recent discoveries of several larger dinosaurs prove otherwise.

All size estimates for Giraffatitan are based on one specific specimen, a subadult individual between 21.8–22.5 metres (72–74 ft) in length and about 12 meters (39 ft) tall. Mass estimates are varied and range from as little as 15 tonnes (17 short tons) to as much as 78.3 tonnes (86.3 short tons) but there is evidence supporting that these animals could grow larger.