L. Peter Deutsch Alive
Wrote the Smalltalk-80 VM, the Lisp 1.5 PDP-1 implementation at age ~17, and later Ghostscript.
19251950197520002025
Wrote the first Smalltalk-80 VM, created Ghostscript (the free PostScript interpreter), and wrote the JIT techniques paper (1984) that modern VMs still cite.\n\nAt 18 he wrote the PDP-1 Lisp; one of the field's quietest implementers of impossible things.