He grew up in Los Angeles and came to the Bay Area with his new bride to work in the Richmond shipyards during World War II.
After the war, he moved his growing family to San Carlos, where he started Thor Madsen Plumbing.
He was active in local civic affairs and served on the San Carlos City Council from 1970 to 1973, and as mayor in 1973. He also was appointed to serve as a liaison between the mayors of San Mateo County and San Francisco.
Mr. Madsen was executive director of the Peninsula Builders Exchange. In 1981 he and business associates founded the Bay Area Bank of Redwood City. He was a founding father and lifetime member of the PACE organization.
A member of the Lions Club, 75 Club, Squires Club, Elks Club and Athletics Club, Mr. Madsen also was an avid fisherman, bridge player and gardener. He also enjoyed world travel, say family members.
Survivors include his three children, Barbara Woodward of Del Mar, John Madsen of Palo Alto, and Carolyn Caine of Los Angeles; seven grandchildren; and four great-grandchildren.
At his request, there will be no services. Memorial donations may be sent to The Peninsula Humane Society, 12 Airport Blvd., San Mateo, CA 94401; or the Boys & Girls Clubs of the Peninsula, East Palo Alto branch, 2031 Pulgas Ave., Palo Alto, CA 94303.