The Night King (Game of Thrones)
When a completely different Night King arrived during season 6, Game of Thrones apparently didn’t expect anyone would notice. They also didn’t anticipate that Starbucks coffee cup would be noticed, but hey. Vladimir Furdik, who had previously played the first White Walker Jon Snow killed, took over for Richard Brake, who had previously played the original Night King.
Beric Dondarrion (Game of Thrones)
Of course there is another cast member from Game of Thrones on this list. Fun fact: He is the second actor to be recast out of freaking ELEVEN because it seems that this show cannot commit. An example would be replacing David Michael Scott as Beric Dondarrion after one episode with Richard Dormer in the hopes that no one would notice.