Ankylosaurus is a genus of ankylosaurid dinosaur. Originating from Late Cretaceous North America, this living tank of a dinosaur is the largest and most well-known ankylosaur due to its body armor and tail club.

The largest armored dinosaur, and namesake of said group, measuring between 6 and 8 meters (20 and 26 ft) long and weighing between 4 and 8 metric tons (8,818 and 17,600 lb) – smaller than the Jurassic Franchise canon, which is closer to the initial estimated size of 10 meters (33 ft) – Ankylosaurus was first discovered by Barnum Brown between 1906 and 1908, in the Hell Creek Formation in Montana, four years after the famous paleontologist, known as "Mr. Bones", had discovered Tyrannosaurus. The first fossils found were a collection of bones including two teeth and a skull fragment, although Brown actually unearthed numerous osteoderms in 1900, but incorrectly attributed them to Tyrannosaurus. There was controversy at the time as to whether this was a new genus with so few bones available. Further Ankylosaurus fossils (including a complete skull) as well as the only known club-tail specimen were found in Canada in 1910 by an expedition to the Scollard Formation in Alberta, Canada. Even though a complete skeleton has never been discovered, paleontologists have a very good idea of how this dinosaur looked, by studying its very close relative and predecessor Euoplocephalus.