Are Friday-night dramas television’s most endangered species? Two hour-long series (“That Was Then” and “Providence”) already have been canceled, and several others face uncertain futures. Tom Sizemore’s gritty “Robbery Homicide Division” on CBS has yet to grab many viewers away from NBC’s “Law & Order: SVU.” Apparently, viewers just don’t want to switch an “SVU” for an “RHD”; call it an initial reaction. While the intense Sizemore is always fun to watch, his show lacks the easy chemistry of “SVU”‘s Mariska Hargitay and Christopher Meloni. According to my crystal ball, look for “Robbery” to move to Saturdays (to replace the moribund “Touched by an Angel”) or to disappear.

Fox has had problems with Friday nights ever since “The X-Files” moved to Sunday nights in fall 1996. Remember “The Visitor”? “Ryan Caufield: Year One”? “freakylinks”? “Pasadena”? I didn’t think so. To be fair, I completely forgot about “freakylinks,” and I even wrote a review of that short-lived show. Look for “Firefly” to join their ranks before too long. A quick cancellation would be a sadder fate for “John Doe,” a quirky detective drama that deserves better. Maybe now that the World Series is over, and Fox’s schedule gains some consistency, the audience for “Doe” will grow.

CBS hopes that “Hack,” the new drama about a corrupt cop turned vigilante cab driver, will emerge as one of the surprise hits of the season. Critics, including yours truly, slammed “Hack” for its over-wrought dialogue and predictable stories. But viewers seemed willing to hop in the cab. In its opening weeks, “Hack” ranked among the top-40 shows. But the audience for this Philly cabby has already begun to dwindle.

Since ABC doesn’t have much of a Friday-night lineup to promote, its kicking off November sweeps with a blockbuster: director Ridley Scott’s ultra-violent 2001 sword-and-sandal drama “Gladiator” (8 p.m., ABC) won five Oscars, including a Best Actor prize for Russell Crowe. Joaquin Phoenix turns in a memorable performance as Rome’s decadent emperor. Derek Jacobi and Richard Harris (who died only last week) also appear in this smart and stylish film that is a historical epic, an action thriller and a powerful indictment of contemporary entertainment culture.

Tonight’s other highlights

Scheduled on “48 Hours Investigates” (7 p.m., CBS): a wife and mother disappears and her husband fears that their children might be next.

Winona Ryder stars in the 1996 adaptation of Arthur Miller’s witch hunt drama “The Crucible” (7 p.m., AMC).

Scheduled on “Dateline” (8 p.m., NBC): a Florida reporter receives a life-saving gift from a stranger.

Karen falls under suspicion on “John Doe” (8 p.m., Fox).

Michael Payne helps four couples reconcile their interior-decorating squabbles on four consecutive episodes of “Designing for the Sexes” (8 p.m., HGTV).

A boy’s guardian may be behind his gruesome murder on “Law & Order: Special Victims Unit” (10 p.m., NBC).

Cult choice

Two brothers (Steve Zahn and Paul Walker) trifle with the wrong trucker in the taught 2001 thriller “Joy Ride” (5:20 p.m., Cinemax), co-starring Leelee Sobieski.

Series notes

Freaky Halloween surprises on “Providence” (7 p.m., NBC) … Sword play on “Firefly” (7 p.m., Fox) … Tom Bergeron plays host to “America’s Funniest Home Videos” (7 p.m., ABC) … Animal rights on “What I Like About You” (7:30 p.m., WB).

Scooby and Shaggy pay a visit on “Sabrina, the Teenage Witch” (7:30 p.m., WB) … Mike becomes the chauffeur for a loan shark on “Hack” (8 p.m., CBS).

An awkward dating situation on “Reba” (8 p.m., WB).