Fox Mulder and Dana Scully (David Duchovny and Gillian Anderson), The X-Files

Great partners challenge one another: Strict Catholic and skeptical scientist Scully did her best to debunk Mulder's wild ideas about aliens and shadowy government organizations, on which he began fixating after his sister mysteriously disappeared. After seven years spent sorting out the mysteries of the universe together, Mulder made a believer out of Scully. And all he had to do was get abducted by space creatures himself! Whichever side of the "we are not alone" debate you come down on, there's no arguing that the chemistry between these two is out of this world.