When popular books or comics are used as a basis for television series, additional roles are often created to round out the cast or add a new element to help the story translate into a new medium. Despite not being part of the original story line, characters created for tv often become integral to the plot. Sometimes new roles come to exist almost by accident but end up taking a central position among the existing cast. Here’s a look at a few characters who were created for television and took over starring roles.

Daryl Dixon

This expert tracker, an immensely popular addition to “The Walking Dead” television series, came to be when the show’s writers decided that they liked the audition of actor Norman Reedus so much that they needed to create a new role specifically for him. After one season as a member of the recurring cast, the character became a series regular. Despite not appearing in the comics that spawned the series, Dixon has survived longer on the show than most of the other characters. He has risen to the level of main sidekick to the show’s hero and is a favorite of fans and critics.

Talisa Maegyr

This Game of Thrones healer and love interest created confusion among fans of the books upon which the series is based. She clearly fit into the storyline in a place previously occupied by another character, but had a different name. This led some fans to wonder if she represented the literary character in disguise. Over time fans realized that she was her own, new version of the character who had previously taken her place in the narrative. Talisa Maegyr may have stolen the show primarily because of the controversy she created; many fans felt that she didn’t fit well in the series and that her personality and story line were inconsistent with the tone of the series as originally written by the author. Although she came to play a central role, Talisa Maegyr was brutally killed off at the end of her second season on the show.

Harley QuinnHarley

Sometimes characters created for television become so popular that they end up being written into the material upon which the television show is based. This was the case with supervillain Harley Quinn, who was introduced into the 1990s Batman animated series. This Joker girlfriend and accomplice proved so popular among fans that she was soon incorporated into the Batman comic book series and even listed among the top 50 comic book villains of all time.

When a character in shows like these becomes a central figure, themed toys are never far behind. For a variety of toys and figures based on these and other well-known characters, visit Toyzoo.