Cornwall is home to many legendary tales. Most notable are those of the giants of Cornwall who seemed to have occupied every high space in Cornwall at one time. Jack the Giant Killer - famous throughout the world also has his origins in the legends of the Penwith area of Cornwall, his early exploits included the killing of the giant of St Michael's Mount.
The famous Celtic legend of Tristan and Isolde also has its origins and settings in Cornwall, there is a stone ancient monument near Fowey called the Tristan stone which is said to be the memorial to the real historical Tristan.
(The Mermaid Pew Carving in Zennor Church click on image to enlarge)
Mermaids are also a favourite topic of Cornish legend, the most famous being the tale of the Mermaid of Zennor an account appears below from Wikipedia of the free online encyclopedia.
There is a local legend about a mermaid in Zennor. Matthew Trewhella was a good-looking young man with a good voice. Each evening Matthew would sing the closing hymn at the church in Zennor, solo. A mermaid living in neighbouring Pendour cove was enchanted by the music. She dressed in a long dress to hide her long tail and walked a bit awkwardly to the church. Initially, she just marvelled at Matthew's singing before slipping away to return to the sea. She came every day, and eventually became bolder, staying longer. It was on one of these visits that her gaze met Matthew's, and they fell in love. However, the mermaid knew she had to go back to the sea or die. As she prepared to leave, Matthew said "Please do not leave, who are you, where are you from?".
The mermaid told him that she was a creature from the sea and that she must go back. Matthew was so love-struck that he swore he would follow her wherever she went. Mathew carried her to the cove and followed her beneath the waves, never to be seen again.
In 2009 during family history research found a death record of an ancestor named Matthew Trewheela the cause of death being named as "lured to sea by mermaid!!".