Dennis R. Washington (born 1934) is a Montana-based industrialist and philanthropist who owns, or co-owns controlling interest in, a large consortium of privately held companies collectively known as the Washington Companies and, in Canada, another collection of companies known as the Seaspan Marine Corporation. With an estimated current[update] net worth of around $4.2 billion, he is ranked by Forbes as the 58th-richest person in America.
Born in Spokane, Dennis Washington grew up in Spokane, Bremerton, Washington, and Missoula, Montana. Following graduation from high school, he worked in construction in Alaska and Montana. He began his business career at age 30 in 1964, with a $30,000 loan and a single bulldozer. He created Washington Construction, which worked primarily on highway contracts and by 1969 was the largest contractor in Montana.
In the 1970s he moved into mining and dam construction. In 1986 he acquired a copper and molybdenum mine at Butte, Montana. He successfully reopened the mine and it became a very profitable operation. This success helped him diversify into railroads, marine services, coastal shipping, aviation and real estate. In 1996 Washington Construction acquired global construction and engineering company Morrison-Knudsen Corporation of Boise, Idaho, creating Washington Group International.
Dennis Washington also owns a large private estate on Stuart Island, British Columbia, including a luxury fishing lodge and golf course. The Washington-Grizzly Stadium for football at the University of Montana is named for him. He also provided the yacht Attessa featured in the film Overboard 
Included in the Washington Companies' holdings are: