[1] Christmas was born in Waterford, son of Richard Christmas, High Sheriff of Waterford in 1686, and Susanna Aland, daughter of Henry Aland, and was educated at Trinity College, Dublin.
[3] Like his father and his grandfather, the elder Thomas Christmas, he was High Sheriff of Waterford (1715).
The Christmas family were dominant in Waterford politics from the late seventeenth century up to the 1860s.
He married Elizabeth Marshall, daughter of John Marshall of Clonmel (died 1717), and sister of Robert Marshall, judge of the Court of Common Pleas (Ireland); Robert is best remembered as the executor and co-legatee of Esther Vanhomrigh, the beloved "Vanessa" of Jonathan Swift.
After his early death, Catherine remarried Theophilus Jones and had three sons.