I have no idea, but gosh Christian looks hot in that pic!

Cary Grant-->Katherine Hepburn (Philadelphia Story)-->Jane Fonda (On Golden Pond)-->J. Lo (Monster in Law)-->Matthew McConaughey (The Wedding Planner)-->Christian Bale (Reign of Fire)

WaBAM!

WaBAM is right! Much longer, but I'm still proud:
Cary Grant (North by Northwest) --> Alfred Hitchcock (Notorious) --> Gregory Peck (To Kill a Mockingbird) --> Robert Duvall (The Godfather) --> Marlon Brando (Don Juan de Marco) --> Johnny Depp (Public Enemies) --> Christan Bale

Haha! After three days of thinking about it, I have finally got it!

Cary Grant to Katherine Hepburn (Bringing Up Baby) to Jane Fonda (On Golden Pond) to Robert Redford (Barefoot in the Park) to Scarlett Johanssen (The Horse Whisperer to Christian Bale (The Illusionist)

Christian Bale and Scarlett Johanssen were in The Prestige, the Illusionist was the one with Edward Norton. :)

Cary Grant to Walter Matthau in Charade
Walter Matthau to Kevin Costner in JFK
Kevin Costner to Morgan Freeman in Robing Hood: Prince of Thieves
Morgan Freeman to Christian Bale in Batman Begins

Haha, I just noticed that I called it Robing Hood. Just pretend there's no g there.