Clarence Melvin Zener was the American physicist who first (1934) described the property concerning the breakdown of electrical insulators. These findings were later exploited by Bell Labs in the development of the Zener diode, which was duly named after him. Zener was a theoretical physicist with a background in mathematics who conducted research in a wide range of subjects including: superconductivity, metallurgy, ferromagnetism, elasticity, fracture mechanics, diffusion, and geometric programming.

A Zener diode is a special type of diode designed to reliably allow current to flow "backwards" when a certain set reverse voltage, known as the Zener voltage, is reached.