Smaug vs Ancalagon by Valonia-Feline on DeviantArt

Glaurung, The One Wiki to Rule Them All

Comparison of the Dragons of Middle-Earth

Dragons, The One Wiki to Rule Them All

Ancalagon the Black makes Smaug look like a little baby which just emerged from egg. - 9GAG

The One Ring :: View topic - Glaurung the Golden

Acnologia vs Ancalagon and Glaurung - Battles - Comic Vine

What is the size difference between Ancalagon the Black and Smaug? - Quora

Juan de Santiago - Senior Asset and Creature Artist - All

Who would win balerion from asoiaf or ancalgon the black from tlotr universe : r/gameofthrones

Smaug - Wikipedia