John Charles Reynolds (June 1, 1935 – April 28, 2013) was an American computer scientist.

He wrote a seminal paper on definitional interpreters, which clarified early work on continuations and introduced the technique of defunctionalization.

He worked on a separation logic to describe and reason about shared mutable data structures.

The conceptual integrity of the language made it one of the main objects of semantic research, along with Programming Computable Functions (PCF) and ML.

He won the ACM SIGPLAN Programming Language Achievement Award in 2003, and the Lovelace Medal from the British Computer Society in 2010.