James Henry Gillis (14 May 1831 – 6 December 1910) was a rear admiral in the United States Navy.

Gillis served on the frigate USS St. Lawrence at the beginning of the Civil War, he participated in the defeat of the rebel privateer Petrel on July 28, 1861 off South Carolina.

[2] After the Civil War, he became a member of the District of Columbia Commandery of the Military Order of the Loyal Legion of the United States.

Rear Admiral Gillis died at Melbourne Beach, Florida at the age of 79.

He was interred at Arlington National Cemetery, where his tombstone bears his final active-duty rank of commodore.