Edsger Dijkstra was a pioneer in computing. Yet he lived like a luddite. He did not own a television or go to the movies and did not even own a personal computer until much later in his career! He enjoyed playing the piano and left behind a large amount of papers and documentation - both personal and technical.
Leslie Lamport wrote one seminal paper after another in the field of distributed computing and concurrency. He co-created LaTex and the Paxos algorithm. He then rigorously defined the temporal logic of actions (TLA) which is a mathematically correct basis for a checking a program's behaviour/models at a high level. I took his TLA+ web course recently. The presentation of the course is fantastic. His mirthful yet sincere attitude really shines through in it.
Are there any pioneering researchers who you find fascinating?
Hawking was great, and wrote a fantastic book called "God Invented the Integers" where he details fascinating seminal math contributions.
I'm a geek for Horn and Johnson of Matrix Analysis fame.
Munkres topology has been bedtime reading for a long time.
Quite a few philosophers strike my fancy, especially the existential school.
Brilliant. I'll be sure to share this with my electronic-engineer colleagues on the High Tech Campus (the former Philips Research campus) here in Eindhoven. :)