Euthydemus I (c. 260 BCE – 200/195 BCE), Greco-Bactrian king in about 230 or 223 BCE according to Polybius, is thought to have originally been a Satrap of Sogdiana, who overturned the dynasty of Diodotus of Bactria and became a Greco-Bactrian king.

Strabo, on the other hand, correlates his accession with internal Seleucid wars in 223/221 BCE.

His kingdom seems to have been substantial, including probably Sogdiana to the north, and Margiana and Ariana to the south or east of Bactria.