Kelsey Grammer shows off his versatility this week. On Monday, the “Frasier” star hosted the president and first lady at Ford’s Theatre. Tonight he becomes a rat. Grammer provides the voice and serves as executive producer for the new primetime cartoon “Gary the Rat” (9:30 p.m., TNN), part of a new two-hour, adult-themed animation block aimed at younger men.

“Gary” was to have been part of the launch of the newly monikered Spike TV network. But that debut has been scuttled by a lawsuit from filmmaker Spike Lee, who claims that the network’s name and lowbrow image would harm his reputation. The legal brouhaha has kept the word “spike” in the news, resulting in a publicity bonanza for the network, whatever it’s eventual name.

“Gary” concerns a viciously successful New York lawyer who wakes up one day to discover that he has become a giant rodent. The transformation does not crimp his courtroom style, so he continues to badger juries in his designer suits. While the idea of a modern-day riff on Kafka’s “The Metamorphosis” sounds witty, “Gary” is anything but. Gary’s mean-spirited nature manifests itself in curt phone conversations with his mother, who sounds as if she’s confined to the psychiatric wing of a grim old-folks home.

If catheter jokes are your cup of tea, then “Gary’s” for you.

TNN’s other new animated features include “The Ren & Stimpy Adult Party Cartoon” (9 p.m.), repeats of the original “Ren & Stimpy” cartoons (10:30 p.m.), and “Stripperella” (10 p.m.), created by Stan Lee. Pamela Anderson lends her voice, image and overall reputation to the pneumatic spy Erotica Jones, who fights bad guys when not wrapping herself around a pole at an exotic dancing establishment.

Tonight’s other highlights

• One competing pair begins to question their compatibility on “Amazing Race 4” (7 p.m., CBS).
• Michelle Pfeiffer and George Clooney star in the 1996 romance “One Fine Day” (7 p.m., ABC).
• A teen tries to fit in with the country-club set in the 2000 mystery “The In Crowd” (7 p.m., WB).
• Tim Robbins and Rob Schneider appear on “Primetime Glick” (7 p.m., Comedy Central).
• Scheduled on “Primetime” (9 p.m., ABC): Car leaseholders who commit insurance fraud; a repeat interview with Debbie Mathers-Briggs, the mother of performer Eminem.

Late night

The Piedmont Bird Callers, Luke Wilson and musical guest Yeah Yeah Yeahs appears on “Late Show with David Letterman” (10:35 p.m., CBS) … Jay Leno hosts Arnold Schwarzenegger, Snoop Dogg and Blu Cantrell on “The Tonight Show” (10:35 p.m., NBC).