Ginger Island NPC Overhaul is mod created to work for Stardew Valley that made a lot of changes to the NPCs located at the Ginger Island on the map.

Who are the NPCs included in the changes?
Birdie, Professor Snail, The Gourmand Frog, and Leo are the ones whom you can change the skin used.

As for Bidie, as her skin was modified, her background story is also somehow altered.
As for Professor Snail, after the skin, his dialogues are somehow modified as well.
For The Gourmand Frog, his dialogue sounds plainer.
And for Leo, as his appearance was changed as well, his background storyline also changes.