9. The Fisher King - Merlin
Another Game of Thrones alumni making an appearance on our list, here we have the mighty Donald Sumpter in one of his most overlooked and largely underrated roles to date.
Coming during the Merlin Season 3 episode, The Eye of the Phoenix, Sumpter makes a one-off appearance as The Fisher King Merlin, Gwaine, and Arthur are attempting to find during a quest. We learn that said Fisher King was a sorcerer seriously injured in battle many years ago. His wound was then said to have become badly infected and this infection spread through both his body and his kingdom as well.
It isn't known whether or not the legends about the mythical figure are true, that of him being kept alive by magic in a castle. That is, until Merlin comes face-to-face with the man himself in his throne room. Merlin is offered precious water from the Lake of Avalon by the withered being, with The Fisher King asking only that he be put out of his misery in exchange.
Our hero reluctantly obliges, handing over a phoenix eye bracelet he'd saved Arthur from earlier in the quest to cap off both the life of a legend and a hauntingly beautiful scene.