- The Intel i432 - too far ahead of its time, in Itanium for the 1980's. https://en.wikipedia.org/wiki/Intel_iAPX_432
- The TI CMS320 series of DSPs. So full of silicon bugs it hurt TI badly.
- The Transputer T9000 - very ambitious, but vapourware for so long it killed its parent company. https://en.wikipedia.org/wiki/Transputer#T9000