I can think of only two really famous twentieth-century monsignors. I’m excluding Fulton Sheen since he went on to be a bishop—and I’m too modest to put myself on the list!
The two famous monsignors were both writers and both were received into the Catholic Church from the Church of England. Both of them were the sons of Anglican archbishops, one who was even the Archbishop of Canterbury.
Monsignor Ronald Knox was a brilliant wit and a classical scholar. His one-man translation of the Bible is a beautiful book and just one literary accomplishment among many.