Daniel O'Brien, 4th Viscount Clare (died 1693) was the son of Daniel O'Brien, 3rd Viscount Clare and Philadelphia Lennard. He was commander of a regiment which he conveyed to France where he fought in the Battle of Marsaglia on 4 October 1693 and was mortally wounded. Daniel O'Brien never married and was therefore succeeded by his brother Charles O'Brien, 5th Viscount Clare.