Gwanggaeto the Great of Goguryeo (374–413) (r. 391–413) is the nineteenth monarch of Goguryeo, the northernmost of the Three Kingdoms of Korea.

His full posthumous name roughly means "Very Greatest King, Broad Expander of Territory, buried in Gukgangsang.

", sometimes abbreviated to Hotaewang or Taewang.

He selects Yeongnak as his era name, and is called Emperor Yeongnak during his reign.

Under Gwanggaeto, Goguryeo once again becomes a major power of East Asia, having enjoyed such a status in the 2nd century CE.

Upon Emperor Gwanggaeto's death at thirty-nine in 413, Goguryeo controls all territory between the Amur and Han Rivers (two thirds of modern Korea, Manchuria, and parts of the Russian Maritime province and Inner Mongolia).

In addition, in 399, Silla submits to Goguryeo for protection from raids from Baekje.

Gwanggaeto captures the Baekje capital in present-day Seoul and makes Baekje its vassal.

Many consider this loose unification under Goguryeo to have been the only true unification of the Three Kingdoms period.

Gwanggaeto's accomplishments are recorded on the Gwanggaeto Stele, erected in 414 at the site of his tomb in Ji'an along the present-day Chinese-North Korean border.

It is the largest engraved stele in the world.