To be nostalgic for “Happy Days” is to be nostalgic for nostalgia itself. And that’s a little weird. But maybe that’s the point of the “Happy Days 30th Anniversary Reunion” (7 p.m., ABC).

Early in the proceedings, creator Garry Marshall recalls some sage advice from fellow producers, who suggested that if they made a show set in the past the reruns would never look old. As peculiar as that sounds, Marshall’s mentors were absolutely correct. Because “Happy Days” was a show made in the 1970s set in an antiseptic and mythical 1950s, it remains oddly timeless.

As Marshall and star Ron Howard relate, the original pilot was made before the ’50s nostalgia craze erupted in the early and mid-’70s. According to Howard, the pilot was strongly influenced by the popular 1971 coming-of-age film “Summer of ’42,” a film obviously not set in the ’50s.

Although ABC canned the pilot, they salvaged pieces of it for a short segment on “Love American Style.” It was that show that brought Ron Howard to the attention of George Lucas while he was casting “American Graffiti.” And, Marshall explains, it was the surprising success of “Graffiti” that made ABC execs return to him and ask him to re-shoot his Eisenhower-era sitcom.

Tonight’s other highlights

• Summer gets serious about her comic book on “The O.C.” (7 p.m., Fox).
• Eddie Murphy stars in the 1998 comedy “Dr. Doolittle” (7 p.m., WB).
• On back-to-back episodes of “CSI” (CBS), a serial killer of cops (7 p.m., r), the honeymoon ends for two mail-order brides (8 p.m.).
• All heck breaks loose after a meteor shower lights up the heavens on “Point Pleasant” (8 p.m., Fox).
• Pratt takes a special interest in a gunshot victim on “ER” (9 p.m., NBC).

Late night

Elton John and Eva Mendes appear on “Late Show with David Letterman” (10:35 p.m., CBS) … Jay Leno hosts Jamie Foxx and LeAnn Rimes on “The Tonight Show” (10:35 p.m., NBC).

Maroon 5 performs on “Late Night with Conan O’Brien” (11:35 p.m., NBC) … Craig Ferguson hosts Laila Ali on “The Late, Late Show” (11:37 a.m., CBS).