Princess Myrcella, sister to Joffrey, was originally played by Aimee Richardson in seasons one and two.
Actress Nell Tiger Free took over for season five, when Myrcella was a little more grown up.
Tommen Baratheon was also recast. Here's Callum Wharry as the youngest of Cersei's children in season one.
Dean Charles Chapman took over starting in season four. The showrunners needed to age him up for a pending marriage consummation.
This is what Gregor Clegane (The Mountain) looked like in season one when Conan Stevens played the brutish man.
But he was recast in season two, and actor Ian Whyte took over briefly. The two look very similar.
But then a third Gregor came along! Icelandic strongman Hafþór Júlíus Björnsson portrayed The Mountain in seasons three through five.
David Michael Scott was originally cast to play Beric Dondarrion, a minor but important character in season one.
Beric was offscreen for season two, but Richard Dormer returned as his incarnation in season three.
Daario Naharis, the sellsword who seduced Daenerys, was played by Ed Skrein at the end of season three.
Season five's Daario was strikingly different when Michiel Huisman took over.
