Getting your Trinity Audio player ready...

Fifteen years ago, if you asked where old stars popped up to remain visible on TV, the answers were easy and obvious: “The Tonight Show Starring Johnny Carson” was one place they always were welcome, and Aaron Spelling’s “Love Boat” and “Fantasy Island” were others. But Carson is gone, and Spelling is fixated on the “Melrose Place” generation.

So where do the stars of yesteryear show up today? One place they can find work on TV is as relatives: Robert Culp as Ray’s father-in-law on “Everybody Loves Raymond,” Connie Stevens as the mother of Pamela Anderson Lee’s C.J. on “Baywatch,” Carol Burnett and Carroll O’Connor as the parents of Helen Hunt’s Jamie on “Mad About You,” etc.

But not everything’s relative. There are other guest and regular roles to be filled, with some shows more open and willing to dip back in TV history to fill them.

In comedy, you can start with NBC’s “Mad About You,” where a love of TV’s past is obvious. Not only do Burnett and O’Connor show up, but the sitcom slowly but surely is working its way through the cast and writers of TV’s classic “Your Show of Shows” variety series: Sid Caesar and Mel Brooks (as well as Burnett) are up for Emmys for their “Mad About You” guest shots this year, and Carl Reiner won an Emmy for his guest shot on the show last year.

In drama, the nostalgia leader is the CBS Dick Van Dyke series “Diagnosis Murder.” Not only does Van Dyke himself qualify in this regard, but the guest casting shows a loving regard not only for veteran performers, but for the old roles they used to play.

Just as Reiner, for “Mad About You,” reprised his Alan Brady role from “The Dick Van Dyke Show,” Van Dyke’s new show has brought back Mike Connors of “Mannix” and Andy Griffith of “Matlock” — both of them in character. The fifth-season premiere features such TV cop-show vets as Angie Dickinson, Fred Dryer, Martin Milner and Kent McCord, a TV blast from the past so potent Van Dyke’s “Diagnosis Murder” ought to be renamed Dick at Night.

Where else can old TV soldiers go when they don’t want to fade away?

Not surprisingly, given its more mature demographic, CBS offers the most alternatives. In addition to “Diagnosis Murder,” there is the veteran-friendly casting of “Touched by an Angel” (Esther Rolle, for example), and “Dr. Quinn, Medicine Woman” gets credit solely for hiring Orson Bean.

“Cybill” not only has showcased Cybill Shepherd, but has given much more challenging work to former “Dukes of Hazzard” star Tom Wopat and handed a strong recurring role to Morgan Fairchild.