Nanu! Nanu!. Robin Williams’ Mork from Ork...

Nanu! Nanu!. Robin Williams’ Mork from Ork beams down for another visit to the Cunningham household on Happy Days (Monday at 6:05 a.m. on TBS).

Chad Everett guests on a two-part Police Story (Monday-Tuesday at 3 p.m. on A&E;) in which the police enter into negotiations with hostage takers.

TBS repeats 30 Years of Andy: A Mayberry Reunion (Wednesday at 7:35 p.m. on TBS), a 1990 special featuring “The Andy Griffith Show” cast members Don Knotts, Betty Lynn, Hal Smith and George Lindsey sharing their memories about their favorite episodes, including “My Fair Ernest T. Bass” and “Fun Girls.”

Dick Gautier guests on Bewitched (Wednesday at 8:30 p.m. on Nickelodeon) as a Paris dress designer.

Tom Poston plays Bob’s old friend “The Peeper” on The Bob Newhart Show (Wednesday at 11 p.m. on Nickelodeon).

Before they became TV stars, Mandy Pantinkin and Tom Selleck appeared on Taxi (Thursday at 10:30 p.m. on Nickelodeon) in the episode in which the cabbies reminisce about Cab 804.

Tom Hanks plays a college student who’s involvement in a medieval fantasy world game leads to murder in the 1982 TV-movie Rona Jaffe’s Mazes and Monsters (Saturday at 12:05 a.m. on TBS).

Little Dog Lost (Saturday at 3:30 p.m. on the Disney Channel) is a 1963 episode from “The Wonderful World of Color” about a runaway Welsh corgi puppy.