St. Damien - the Leper Saint
One of our "adopted" American saints who should be much better known is St. Damien of Moloka'i.
He heroically served the lepers of the then-Kingdom of Hawaii in the late 19th century.
Like so many of the saints such as Peter Claver, Katherine Anne Drexel (other saints of the Americas) he gave his life serving those whom no one else was willing to serve.
You can start reading about him here. If you are lucky enough to travel to Hawaii, there are shrines to him there.