John Tyler was the 10th President of the United States of America, serving in office from 1841-1845. While he may not be the most widely remembered or revered Presidents, he is the earliest one to still have living grandchildren.
In August of 1853 John Tyler and First Lady Julia Gardiner Tyler had a son, Lyon Gardiner Tyler. Lyon grew up to become an educator and historian, as well as president of the College of William and Mary. He married twice due to the death of his first wife. With his second wife he had three children, One child died as an infant but the remaining two, Lyon Gardiner Tyler Jr and Harrison Ruffin Tyler, are still alive as of 2015.