Ed Sheeran
Not just anyone gets to guest star on Game of Thrones. The famous show had every actor wishing they could be cast, but only cast members could request guest star cameos. Since Maisie Williams was such a big fan of pop star Ed Sheeran, the producers hired him to play a traveling soldier. The cameo even included a little song. They didn't tell her until she showed up to set and saw Sheeran sitting there.