Mulder and Scully had it. So did Angel and Buffy.

Jim and Pam definitely have it. As do Bones and Seeley.

Shows like “The X-Files” and “Bones,” that rely on the chemistry of their leads – specifically relationships between the opposite sexes that are heavy with sexual tension – are present throughout TV’s history. The latest example of this tried and true formula is “Castle.”

The chemistry is definitely intriguing between the main characters, two total opposites: successful mystery author Richard Castle (Nathan Fillion, “Firefly”) and aggressive NYPD detective Kate Beckett (newcomer Stana Katic). When a killer starts copying scenes from Castle’s novels, he and Beckett work together to catch the murderer. The pair does so well that they continue on to more unusual cases.

Will the hint of a spark between the duo burst into a hit or will it quietly smolder away? Stay tuned.

“Castle” premiers March 9 and airs Mondays at 10 p.m. on ABC.