3. Spencer Tracy and Katharine Hepburn (Adam's Rib '49, Pat and Mike '52) - This real-life duo may have shared a complicated history, but onscreen they were always pitch-perfect. The pair starred in nine films together, including the classic rom-com Adam's Rib. Their relationship full of tension (affairs, estrangement and major arguments…yikes!), but their witty banter and chemistry made for some amazing cinematic romances.