Hero (or Heron) of Alexandria (c. 10 – 70) was a Hellenized Egyptian engineer and geometer in Alexandria, Egypt. His most famous invention was the first documented steam engine, the aeolipile. He is said to have been a follower of the Atomists. Some of his ideas were derived from the works of Ctesibius.

A number of references mention dates around 150 BC, but these are inconsistent with the dates of his publications and inventions. This may be due to a misinterpretation of the phrase "first century" or a confusion of this Hero with other Heros- Hero was not an uncommon name.

Hero is credited with inventing many feedback control devices using water, fire and compressed air in various combinations, and the first type of analogue computer programming via intricate systems of geared spindles studded with pegs and wound with ropes connected to weights (trays of sand emptying over time) used to operate his automatic theaters that included automatic doors and multiple changing scenes of moving figures accompanied by lighting and sound effects.