Arthur Jeffries was a funny minor character on the show. Back when the main characters were children, he had a television show that taught science to kids as Professor Proton.
Unfortunately he was very bitter in his retirement, but Sheldon hires him to give himself nostalgia. And surely enough, Sheldon Cooper does everything in his power to annoy this man to death. And Professor Proton does die eventually.
But he does appear as a Force ghost in Sheldon’s dreams. That man can’t escape Dr. Cooper, even in death.