What is the name of the dragon that attacked Erebor?

The dragon that attacked Erebor was Smaug.

Smaug was a powerful, intelligent, fire-breathing dragon who invaded the Dwarf kingdom beneath the Lonely Mountain. He was drawn by Erebor’s immense wealth and attacked without warning, driving King Thrór and the Dwarves from their home. Smaug also destroyed the nearby city of Dale, forcing its surviving people to flee toward the Long Lake.

For roughly 150 years, Smaug slept beneath the mountain on the Dwarves’ treasure hoard. His occupation of Erebor set the central quest of The Hobbit in motion: Thorin Oakenshield and twelve other Dwarves travelled with Bilbo Baggins to reclaim their homeland. Bilbo discovered a bare patch in Smaug’s jewel-covered underside, and a thrush passed that information to Bard the Bowman.

Bard ultimately killed Smaug with a single arrow at Lake-town. Scatha, Ancalagon, and Glaurung are also dragons in Tolkien’s wider legendarium, but none attacked Erebor. Smaug’s name is also a linguistic joke: Tolkien connected it with an Old English verb meaning “to squeeze through a hole.”