In the end, it was the vagaries of network television that did in Sydney Bristow.

ABC has announced the end of the line for “Alias,” which will conclude its five-season run in May. Skein, which stars Jennifer Garner as CIA agent Bristow, earned critical raves through the years but struggled this season on Thursday nights.

Early announcement will give producers time to wrap up the show’s intricate and involved story arc, and ABC a chance to promote the final episodes as a bigger event.

“This news, and its timing, is a mixed blessing,” said exec producer Jeff Pinkner. “Though we’re obviously very saddened to face the reality that ‘Alias’ is coming to an end, the lasting quality of every good story is determined by its conclusion. This news gives us the freedom to end the series in the climactic way it deserves.”

“Alias” will have hit 110 episodes by the time it signs off in May. The show has spawned several DVD packages, as well as books and a soundtrack. Show also picked up seven Emmy Awards, and Garner landed a Golden Globe Award in 2002 for her role.

The show started out as a drama about a college student who moonlighted as an agent for the top-secret SD-6. “Alias” has taken several twists and turns through the years — including writing Garner’s real-life pregnancy into this season’s episodes.

Moved to a tough Thursday slot this season, “Alias” has averaged a 2.3 rating/6 share and 7.1 million viewers after seven episodes. Show also premiered in off-net syndication this fall, airing weekdays on TNT and weekends on local stations (including the Fox O&Os).

“Right out of the box, ‘Alias’ attracted a cult following of fans that were completely invested in the show,” said ABC Entertainment prexy Steve McPherson. “We owe both the storytellers and fans a sendoff worthy of a show that has been such a part of the pop culture vernacular.”

“Alias” was created by J.J. Abrams, who exec produces with Pinkner, Ken Olin, Jesse Alexander and Jeffrey Bell. Garner, Victor Garber, Ron Rifkin, Carl Lumbly, Kevin Weisman, Balthazar Getty, Rachel Nichols and Elodie Bouchez star.

The Touchstone skein launched Sept. 30, 2001.