Stars from sitcoms past reappear on tonight’s rerun-intensive lineup. “Friends” star Matthew Perry guest stars on “Scrubs” (8 p.m., NBC) as a young man donating a kidney to save the life of his estranged father, played quite convincingly by John Bennett Perry, who happens to be Perry’s real-life dad. Just don’t confuse him with Kathleen Turner, who played Chandler’s gender-bending papa on “Friends.”

The elder Perry, whose numerous film and television credits date back to the early 1970s, also played Matthew Perry’s dad in the 1997 comedy “Fools Rush In.”

John Bennett Perry appeared in the 1984 primetime soap “Paper Dolls.” Set in the world of fashion, modeling and cosmetics, this “Dynasty” knock-off ran for only three months, but developed a cult following nonetheless. That probably had something to do with an over-the-top cast including Mimi Rogers, Richard Beymer, Morgan Fairchild, Nicollette Sheridan, Lauren Hutton and Brenda Vaccaro! The show introduced viewers to a young actress named Terry Farrell (as a character clearly based on real-life model Brooke Shields), who would later star on “Star Trek: Deep Space Nine” and co-star with Ted Danson on “Becker.”

Tonight’s other highlights

¢ “Combat Ready” (7 p.m., Military) looks at the history of war games, from ancient board games to state-of-the-art digital simulations used by policymakers to prepare our armed forces for possible conflicts and future threats.

¢ Reese Witherspoon stars as a beauty caught between two men (Josh Lucas and Patrick Dempsey) in the 2002 comedy “Sweet Home Alabama” (7 p.m., Fox). As in “Miss Congeniality,” Candice Bergen makes the most of a small role.

¢ A small town loses a second teen in as many years on “Without a Trace” (9 p.m., CBS).

¢ A patient from Carter’s distant past brings up old wounds on “ER” (9 p.m., NBC).

¢ Ringo Starr and the Roundheads perform on “Soundstage” (9 p.m., PBS).