‘Six Degrees,’ 10 p.m. ABC ‘Shark,’ 10 p.m. CBS

Tonight, two more shows hoping to put the final stake in the vampire that is “ER” debut.

Each must be considered its network’s best hope. How else to explain their being given the plum spots following ratings powerhouse “CSI” on CBS and the white-hot “Grey’s Anatomy” on ABC?

“Six Degrees” must have gotten its shot largely based on the reputation of its first-billed executive producer, J.J. Abrams. Abrams earned his stripes with the TV classics “Alias” and “Lost.” But he’s now an in-demand film director, so how much will he be available to work on “Six Degrees?”

This esoteric serial is based on the theory that anyone on the planet can be connected to any other person through a chain of six people.

The six characters in “Six Degrees” are a grieving single mother, a public defender, a woman on the run, a self-made career woman with a cheating boyfriend, a limo driver with a gambling addiction and a down-on-his-luck photographer.

Throughout the pilot, the sextet makes connections, and before long, against all odds, the title’s premise is proven.

The key in such a character study is that viewers must care about these characters. And, except for Hope Davis’ grieving mother, Laura, this bunch isn’t all that engrossing. The concept is intriguing, but after the dynamics of “Grey’s Anatomy,” “Six Degrees” may be a little too subtle.

“Shark” understands that if you’re going to do a character study, put a character at the center of it. And while you’re at it, cast a scenery-chewing movie actor in the lead role.

James Woods plays Sebastian Stark, a top-flight defense lawyer who gets an attack of conscience after one of the defendants he gets off violently strikes again.

The publicity-conscious Los Angeles mayor drafts Stark to head up the High Profile Crime Unit, much to the dismay of his former nemesis, District Attorney Jessica Devlin (Jeri Ryan). Devlin gets back at him by saddling him with a group of young stereotypes: the dumb jock from the rich family, the affirmative-action hire, the angry black woman and the ambitious brown noser.

The fun of “Shark” is watching Stark teach his charges the outrageous tactics he used as a defense attorney. They’re appalled but at the same time intrigued. Viewers will be too.

Which, if either, of these two hang around? Their success is going to depend on which of their lead-ins is winning the battle at 9 p.m., even more than how quickly they develop.