This man’s name is John Singer Sargent.
He is considered one of the greatest American portrait painters of his generation (1856-1925).
There are many reasons for this. But just one or two of his sublime works reinforces the statement thoroughly.
If you’re aspiring to be a very strong painter/artist (even digital!), I highly suggest that you read the notes that were transcribed from some of the people who knew Sargent personally, or had been taught by him.