Retherford is one of six wrestlers to ever win the Hodge Trophy multiple times.
Nolf competed with the Nittany Lions from 2014-19.
American will travel to Penn State on Friday, February 21, just before Penn State heads to Big Ten Championships.
Retherford will compete in his first Olympics in the 65-kilogram freestyle category.
Barraclough held a 15-13 record as a Nittany Lion.
Lee will take over for Jimmy Kennedy, who left Penn State to work for David Taylor at Oklahoma State.