10-Mr. and Mrs. Smith, Mr. & Mrs. Smith: So bad, they actually try to kill each other.
8- Batman and Catwoman, The Batman Franchise: Michelle Pfeiffer and Michael Keaton or Anne Hathaway and Christian Bale. Always steamy, always bloody, always...way too much leather.
5- Mickey and Mallory Knox, Natural Born Killers: The title of the movie really says it all plus look at this picture.
4- Boris and Natasha, The Rocky and Bullwinkle Show: They may have not been the most accomplished killers but they were legends!
2- Bonnie and Clyde, Real Life Bank Robbers: In a fictionalized gif.