Karl "Helo" Agathon (Tahmoh Penikett), Battlestar Galactica
In the pilot, the plan was for Lt. Agathon, better known by his call sign "Helo," to be an expendable character and to die when the Raptor leaves him behind on Caprica. Tahmoh Penikett's performance (and no doubt dashing good looks) convinced TPTB to keep him around though, and thus he was fated to fall for Athena and together have a child named Hera. So say we all.
Photo Credits: The CW; John Paul Filo, CBS; Ron Batzdorff/NBC; George Kraychyk/Hulu; NBC; NBC, Peter Kramer/NBC; Gregg DeGuire/Getty Images; Jason LaVeris, FilmMagic; NBC, Chris Haston / NBC; Chris Haston/NBCU Photo Bank/Getty Images; Vivian Zink/Getty Images; Bill Records/NBC via Getty Images