Oliver Blackburn Shallenberger (May 7, 1860 – January 23, 1898) was an American engineer and inventor.
He was born in Rochester in Beaver County, Pennsylvania. His parents were Aaron T. Shallenberger and Mary (born Bonbright). His uncle was William Shadrack Shallenberger.
In 1877 he entered the United States Naval Academy at Annapolis. After his graduation he spent two years on the U. S. flag-ship Lancaster in the Mediterranean, resigning in 1884. The Union Switch and Signal Company, of Pittsburgh, under the management of George Westinghouse, was at that time organizing an electric light department, and Mr. Shallenberger became associated with that work.
In April 1888 he invented an induction meter for measuring alternating current (ampere-hours), a critical element in the Westinghouse AC system.
On November 27, 1889 he married Mary Woolslair. They had a son and daughter. In 1891, poor health required him to resign from the Westinghouse company but he continued as a consultant. In 1897 he had organized the Colorado Electric Power Company.