Kim Alji

Kim Alji (김알지, 金閼智) was a historical figure in Korean history. His descendents formed the Kim royal clan of Silla, one of the Three Kingdoms of Korea.
His legendary birth is said to have occurred during the reign of Silla's fourth ruler, King Talhae of Silla. Though Kim Alji did not rule as King of Silla, his descendants did. Today, 1.7 million South Koreans are in the Gyeongju Kim clan, who trace their genealogy to Kim Alji.

Birth legend
The Samguk Yusa and Samguk Sagi both contain nearly the same story about Kim Alji's birth.
In the year 65 (9th year of Talhae's reign), King Talhae heard a rooster crowing in Sirim, west of Geumseong (Gyeongju, the Silla capital at the time). He sent his minister, Hogong, who was from Japan, to investigate, whereupon Hogong found a golden box hanging on a branch. Light was emanating from the box, and a white rooster was crowing under it.
Hearing this report, the king ordered the box brought to him. When the king opened the box, there was an infant inside. The king was very pleased and reared him. Because he was born from a golden box and was very clever, the king named him "Kim (金, meaning gold) Alji (meaning gold in native korean, with the hanja 閼智 supposed to be read phonetically)". The forest where the box was found was named Gyerim (rooster forest), which also was used as the name of Silla.

This legend is similar to the birth legend of the founder of Silla, Bak Hyeokgeose of Silla (who is said to have called himself Alji Geoseogan).
Modern interpreters have suggested that the Kim Alji may have been the chief of a "gold" (al) clan of northern Korea/Manchuria.