St. Anthony died on June 13, 1231 -- which is why today is his feast day. He was canonized a saint of the Roman Catholic Church only a year later, in 1232. Born in Lisbon, Portugal in 1195, he started off religious life as an Augustinian and ended as a Franciscan. You can read about his remarkable career in Wikipedia or the Catholic Encyclopedia.
But that's not why you know about him.
You know about St. Anthony because of the time you lost your cell phone... or your keys... or the piece of paper with the phone number of that cute girl in the marketing department and this little bit of doggerel came into your head:
Tony, Tony, turn around
Something's lost that must be found
That's not a nursery rhyme; it's a rather irreverent prayer.
Yes, for all of his many accomplishments, St. Anthony is best remembered today as the patron of lost articles (and, more seriously, of missing persons).