The nine-year-old boy joined his star parents, his five siblings and members of Pitt's side of the family on a holiday in the Turks and Caicos Islands in the Caribbean, reported Sun online.
And according to Pitt's niece Josie Neal, he did not bring much festive spirit.
She tweeted a quote made by Pax during a meal on the beach on the night of December 24, "Santa is dead to me."