The Old Swans make their appearance in the episode "When Wedding Bells Thaw." They are first seen kissing in a pond, and Ice King was disgusted because of that. The male swan then sucks the female swan through his beak and swallows her, which has a negative influence on Ice King, as he thought that he could eat his future wife (Old Lady Princess) and keep her in his stomach forever. Ice King then changes his mind and says that marriage is the most beautiful thing in the world, and the wedding goes back on. Finn and Jake are originally shocked and confused, but they agree not to tell Ice King that this is not how marriage works, seeing how happy he is.
The swans look like normal swans, except they are very elderly. They have white feathers and orange beaks, and the female is shorter than the male.