Bob Anderson worked as a sword master, fight director, and stunt performer for over five decades in cinema, appearing alongside Errol Flynn, Antonio Banderas, and Mark Hamill.
It was Mark Hamill who outted Bob Anderson as the third piece of the Darth Vader persona in 1983. The actor was joined by James Earl Jones as the voice and David Prowse as the body in creating one of the greatest villains of all time.
According to Bob Anderson's former assistant Leon Hill, David Prowse wasn't good with a sword, and he was unable to properly learn the moves needed for the climatic end fight scene in Star Wars: Episode V - The Empire Strikes Back. So, despite being several inches shorter and nearing 60 years of age, Bob donned the costume and did the scenes himself opposite Mark Hamill, whom he also trained.