Three Laws of Robotics 
Asimov's Revised Laws of Robotics (1985)

Zeroth Law:
A robot may not injure humanity, or, through inaction, allow humanity to come to harm.

First Law:
A robot may not injure a human being, or, through inaction, allow a human being to come to harm, unless this would violate the Zeroth Law of Robotics.

Second Law:
A robot must obey orders given it by human beings, except where such orders would conflict with the Zeroth or First Law.

Third Law:
A robot must protect its own existence as long as such protection does not conflict with the Zeroth, First, or Second Law.