Answer:
President Benjamin Harrison.
Step-by-step explanation:
President Benjamin Harrison placed the first Christmas tree in the White House in the Second Floor Oval Room (then used as a family parlor and library) in 1889. It was decorated with candles, toys, and other ornaments designed to impress the Harrison grandchildren.
First Lady Caroline Harrison helped decorate the tree, which was installed in the second floor oval parlor today's Yellow Oval Room.