A case in point is the spin-off series "Fear the Walking Dead" which looks at the "Walking Dead" universe form a different perspective and has recently had a character crossover (Morgan)- see here for more details: http://walkingdead.wikia.com/wiki/Morgan_Jones_(Fear_The_Walking_Dead)

The "Walking Dead" franchise began with graphic novels. "Harry Potter" much surely mark one of the most successful transmedia franchises, books, films, computer games, lego characters, costumes, and extended fanclubs (UCC Harry Potter Society uses a sorting hat, and the quasi-gothic architecture of UCC as a backdrop).