Giovanni Costigan (1905–1990) was a historian and specialist in Irish and English history.
He received a Master of Arts at the University of Wisconsin–Madison where he earned his PhD.
In 1934 he joined the history department at the University of Washington where he served for 41 years.
He was a staunch critic of American involvement in the Vietnam war.
One Seattle reporter stated Costigan was a "combative man of peace."