Menmaatre Seti I (also called Sethos I after the Greeks) is a Pharaoh of Ancient Egypt (Nineteenth dynasty of Egypt), the son of Ramesses I and Queen Sitre, and the father of Ramesses II.

As with all dates in Ancient Egypt, the actual dates of his reign are unclear, and various historians claim different dates, with 1294 BCE – 1279 BCE and 1290 BCE to 1279 BCE being the most commonly used by scholars today.

The name Seti means "of Set", which indicates that he was consecrated to the god Set (commonly "Seth").

As with most Pharaohs, Seti had several names.

Upon his ascension, he took the prenomen Menmaatre, meaning "Eternal is the Justice of Re.” His better known nomen, or birth name, is technically transliterated as Sety Merenptah, meaning "Man of Set, beloved of Ptah".

Manetho incorrectly considered him to be the founder of the 19th dynasty.