Andrew Tanenbaum is a professor of Computer Science at Vrije Universiteit in Amsterdam, The Netherlands.
He is perhaps most well-known to contemporary students of Computer Science for his excellent published books on a variety of topics. Many of them are in their 3rd or 4th editions as of this writeup. The titles include:
I can personally attest that the first two of these are quite well-written, easy to understand and comprehensive. In addition to being useful and informative, they are written in a humorous, engaging style. The humor often even extends to the front cover of the text. The front cover of Modern Operating Systems still cracks me up - it features an image of several very academic-looking gents with forks in hand dueling and shouting things like put_fork((i + 1) % N - a humorous reference to the so-called "Dining Philosophers Problem" in the study of Operating Systems.
Tanenbaum is also known for authoring the microkernel-based MINIX operating system which is still used in some OS courses, and for his work on the Amoeba system.
He is also famous for a USENET flamewar he once engaged in with Linus Torvalds over the monolithic design of Linux. An archive of their debate can be viewed at: