The Little Mermaid made a cameo appearance in Shrek 2, when Shrek and Fiona are on their honeymoon.
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Shrek 2
She kissed Shrek on his honeymoon on a beach when a wave washed him and Fiona up. Fiona saw this and wasn't happy, so she pulled her by the fin and threw her straight into the ocean. When Fiona drags her back, she flings her in to the sea as she screams, she landed with a splash near two great white sharks who apparently devoured to her death. She is then briefly mentioned by Fiona's Fairy Godmother, explaining that her story has no ogres involved.
