Final answer:
John Singer Sargent was the American artist known for his portraits and he was born in Italy to Mary Newbold Singer.
Step-by-step explanation:
The American artist known for his portraits, who was born in Italy to the former Mary Newbold Singer, is John Singer Sargent. Sargent was born in Italy while his parents were on tour and trained at an art academy in Florence before moving to Paris. He traveled and painted portraits and local scenery, gaining a reputation for his watercolor paintings. After the rejection of his painting of Madame X, he established himself as a portrait painter in London.