If you're ready to move beyond Anna and Hannah, consider this traditional Scandinavian short form of Susanna, historically very popular in its native lands.

Keelin is a form of Keelan, the Anglicized phonetic form of Caelan or Caoilinn, said to be a unisex name but in practice used almost exclusively for boys. Girls would more often be called Keela, Keeley, or Keely.