Elsanna

Elsanna is the family ship between Elsa and Anna from the Disney and Once Upon A Time fandoms.

Disney
Frozen As children, Elsa and Anna were the best of friends, up until Elsa had accidently hit Anna with her ice magic.

Frozen Fever After years of being separated from each other, Elsa was deturmed to make Anna's birthday the best one ever, as a way to make up for the ones she had missed.

Olaf's Frozen adventure When the sisters came to the conclusion that they don't have a family tradition, due to the years where Elsa kept herself away from Anna, Elsa apodized to Anna for being the reason that they don't have one.

Fanon
While Elsa and Anna are sisters, there are fans who treat Elsana as an femslash ship.