Hattusili I (Ḫattušili I) is a king of the Hittite Old Kingdom.

He reigns ca.

1586–1556 BCE (short chronology).

He used the title of Labarna at the beginning of his reign.

It is uncertain whether he is the second king so identified, making him Labarna II, or whether he is identical to Labarna I, treated as his predecessor in Hittite chronologies.