The dragon who guards Princess Fiona’s castle in Shrek is named Dragon.
Dragon appears when Shrek and Donkey enter the castle to rescue Fiona. She initially attacks them, but Donkey distracts her and eventually forms a romantic relationship with her. The character is usually identified simply as Dragon rather than being given a personal name in the films.
Dragon’s role changes dramatically after the rescue. Instead of remaining an obstacle, she becomes an ally who helps Shrek and Fiona at the wedding. Her relationship with Donkey continues through the franchise, and the pair later have six children known as Dronkeys, a blend of “dragon” and “donkey.”
The character is voiced by several performers in different productions, including Frank Welker through vocal effects in the films. Dragon is sometimes confused with other unnamed dragons from fantasy stories, but this character is specifically the guardian from Shrek’s opening adventure.