Mason's film credits include "The Goodbye Girl" and "Chapter Two," while Van Dyke was a cast member of the long-running comedy series "Coach."
They are to play Frankie's parents, Pat and Tag, on the upcoming holiday episode of "The Middle" to air Dec. 8.
"The Hecks count down the 12 days of Christmas with Frankie's parents, Pat and Tag, when they come to town to spend the holiday with the family -- much to Mike's dismay. But when Frankie decides that she wants to take the focus off of the gifts and make it a simple Christmas, Pat and Tag have other ideas," the network said in a synopsis.
Neil Flynn plays Frankie's husband, Mike, on the show.