He was born October 29, 1938, in Blue Earth, the son of Walter and Myrtle (French) Heenan. He was raised and educated in Blue Earth where he was a 1956 graduate of Blue Earth High School. He served in the U.S. Army following high school and returned to Blue Earth where he was married to Janice LaMont on February 13, 1960 at St. Paul Lutheran Church. Denny became an electrician and worked at Gherring Industries in Blue Earth and at Armor Foods in Fairmont for a few years before going to work at 3M in Fairmont. He was an electrician for 3M for 20 years before retiring in 1990. Denny loved being outdoors and was an avid camper and fisherman for many years. He also enjoyed some travel including anywhere he could go on his Harley. He especially enjoyed any time spent with his grandchildren. Dennis "Gramps" Heenan is survived by his wife, Janice Heenan of Blue Earth, his son, Mike (Deb) Heenan of Elmore, his son, Mark (Kristen) Heenan of Blue Earth, his daughter, Denise Heenan (special friend Eric Powell)of Elmore, his son, Todd (Bridgette) Heenan of Blue Earth, his brother, Terry (Deb) Anderson of Las Vegas, his half brother, Rick Heenan of Fairmont, his half sister, Mary (Doug) Byers of Fairmont, his 9 grandchildren and 7 great grandchildren. He was preceded in death by his parents, Father & Mother-in-law, Raymond & Florence LaMont, brother, John Anderson and brother-in-law, Larry LaMont.