This will indeed be a blast from the distant past, as The Big Bang Theory saw Ramona Nowitzi, played by the always hilarious comedian Riki Lindhome, arrive for the first and last time back in the Season 2 episode "The Cooper-Nowitzki Theorem." She was something of an oddball to everyone, in that she was infatuated by Sheldon and his non-wily ways of making smart things happen. Their partnership, for lack of a more uncomfortable word, was strained by Ramona's insistence that research come before all else, and Sheldon cuts ties with his sorta-girlfriend and sorta-assistant. For one of Sheldon's old flames to return after nearly a decade, and in a season finale, you know something or someone is going to burn.