Illiac IV
One of the most infamous supercomputers ever. It used early ideas on SIMD (single instruction stream, multiple data streams). The project started in 1965, it used 64 processors and a 13MHz clock. In 1976 it ran its first sucessfull application. It had 1MB memory (64x16KB).
Its actual performance was 15 MFLOPS, it was estimated in initial predictions to be 1000 MFLOPS. It totally failed as a computer, only a quarter of the fully planned machine was ever built, costs escalated from the $8 million estimated in 1966 to $31 million by 1972, and the computer took three more years of enginering before it was operational.
The only good it did was to push research forward a bit, leading way for machines such as the Thinking Machines CM-1 and CM-2.