Rolf William Landauer (February 4, 1927 – April 27, 1999) was a German-American physicist who made important contributions in diverse areas of the thermodynamics of information processing, condensed matter physics, and the conductivity of disordered media.

In 1961 he discovered Landauer's principle, that in any logically irreversible operation that manipulates information, such as erasing a bit of memory, entropy increases and an associated amount of energy is dissipated as heat.

As part of the two-man team responsible for managing IBM's Research Division in the mid-1960s, he was involved in a number of programs, including the company's work on semiconductor lasers.

He showed that in systems with two or more competing states of local stability, their likelihood depends on noise all along the path connecting them.

[3] Rolf William Landauer died on 27 April 1999 at his home in Briarcliff Manor from brain cancer.