‘Shield’ third-season finale airs tonight on FX

“The Shield” may not get the kind of attention lavished on, say, “The Sopranos.” But tonight, the FX cop show finishes a third season that doesn’t rank far behind the HBO mob drama in quality.

From the beginning, the heart and soul of “The Shield” has been the morally ambiguous Vic Mackey (a mesmerizing Michael Chiklis), the leader of a rogue LAPD strike team.

Only Tony Soprano, among television’s more prominent characters, is as complex as Mackey. One moment, he’s a violent thug and the kind of cop who should scare the daylights out of an average citizen. The next, he’s an emotionally wounded soul crying out for help.

But over three seasons, “The Shield” has developed a rich tapestry of characters around him. This past season, CCH Pounder as Claudette Wyms, a good cop trying to exist in Mackey’s corrupt world; Jay Karnes as geeky detective Dutch Wagenbach; and Benito Martinez as David Aceveda, the precinct’s politically ambitious captain, have all carried large chunks of the story.

In tonight’s finale (10 p.m.), more and more isolated from his family and friends, Mackey continues to lose his grip on the world he has built. Violent and profane, “The Shield” isn’t for everybody, but it is terrific television.