Tom Van Vleck is an American computer software engineer.
He graduated from MIT in 1965 with a BS in Mathematics. He worked on CTSS at MIT, and co-authored its first email program with Noel Morris. In 1965, he joined Project MAC, which is the origin of the MIT Computer Science and Artificial Intelligence Laboratory.  He worked for development of Multics for more than 16 years at MIT and Honeywell Information Systems.  Since 2007, most of the Multics source code and documentation is provided as free software by IS&T at MIT.
He is also known as a computer security expert.