Dennis E. Haack, 70, passed away on Sunday, February 21, 2021 at Mount View Care Center, Wausau. Dennis was born on May 9, 1950 in Cottage Grove, to Edward P. and Shirley E. (Osmundsen) Haack. He was a 1969 graduate of Madison East High School. He was a veteran of the United States Air Force serving in Vietnam from 1969 until his honorable discharge as a Staff Sergeant in 1975. He had been employed as a security guard and private investigator in Las Vegas until 1991 when he returned to Madison where he was employed at Woodman's East until his retirement in 2005 due to health reasons. Dennis enjoyed fishing and was a member of the America Legion Post 153 of Pittsville. He is survived by a sister, Elaine Haack of Cottage Grove and brothers, Larry Haack of Vesper and Dan (Monica) Haack of East Cottage Grove. He is further survived by a nephew, Danny Haack and a niece Kristi (Chris) Maki and their family. He was preceded in death by his parents. Committal services and Military Rites will be conducted at Highland Memory Gardens Cemetery in Cottage Grove at a later date. Memorials may be sent to Larry Haack, 6419 Hemlock St., Trailer 2, Vesper, WI 54489.