Penny Hofstadter (née Teller) is a fictional character from the American CBS sitcom The Big Bang Theory, portrayed by actress Kaley Cuoco. She is the primary female character in the series, befriending her across-the-hall neighbors Leonard Hofstadter (Johnny Galecki) and Sheldon Cooper (Jim Parsons), two physicists who work at the nearby California Institute of Technology (Caltech). Penny's lack of advanced education sets her apart from the group, but her outgoing personality and social aptitude drastically contrasts with the personalities of the primary male characters in the series, so she is considered as "one of them". She is the primary love interest of Leonard, with whom she maintains a brief romantic relationship during the third season, which is later resumed in the fifth season an