Seasons end for every Thursday-night series except “Flash Forward,” which will end its first and only season next week.

“Grey’s Anatomy” (8 p.m., ABC) wraps up its sixth season with a two-hour episode in full cliffhanger mode as an unprecedented crisis fills Seattle Grace with patients, putting Meredith and Cristina’s surgical skills to the test. “The Mentalist” (9 p.m., CBS) ends its sophomore year with hints about its original mystery as a copy cat of the Red John murderer who killed Jane’s family puts the entire team in danger.

NBC’s Thursday night of comedies remains the evening least shaken up by the network’s disastrous 2009 season. The unscripted portion of the evening (“Jay Leno”/”Marriage Ref”) will give way to the anthology series “Love Bites,” which has been described as “Sex and the City” meets “Love American Style.”

The consistently laugh-free “Parks & Recreation” will be bumped off the schedule until at least mid-season by the new sitcom “Outsourced,” about an American worker transferred to India.

Kathy Bates returns on tonight’s season finale of “The Office” (8 p.m., NBC) to put out the publicity inferno resulting from stories of Sabre’s exploding printers.

This series has now exhausted its initial inevitable story arcs surrounding Jim and Pam’s furtive romance, their public romance, engagement, marriage and now parenthood. Perhaps too much story revolved around Michael’s mean-spirited cluelessness this season.

From his gossip about Stanley’s affair, his brutal treatment of Pam’s mother and his defiant infidelity with the very married Donna (Amy Pietz), Michael Scott has been daring both his colleagues and the audience to hate him. So far, few have obliged. But you have to wonder how far “The Office” will push its luck.

Schedule changes will also move “30 Rock” (8:30 p.m., NBC) to 7:30 p.m., next season, not an ideal time for its silly, sophisticated inside-joke-driven comedy.

The season wraps up with Liz juggling three wedding invites. The Emmy-winning series has gotten a tad too slap-sticky at times, and one wonders how many guest stars it really requires.

At the same time, the recent turn by Julianne Moore as Jack’s hometown crush with the wobbly Boston accent has been a joy to behold.

• Fans of “Dirty Jobs” should not miss tonight’s installment of the four-part series “Toughest Military Jobs” (8 p.m., Military Channel). Entitled “Dirt,” it details the kinds of gritty, behind-the-scenes assignments that keep recruits hoping there will still be hot water when they hit the showers.

Tonight’s season finales

• Jeff commands undue attention on “Community” (7 p.m., NBC).

• A hoarder’s remains reveal an abundance of clues on “Bones” (7 p.m., Fox).

• Leslie’s plan for a youth concert face opposition on “Parks & Recreation” (7:30 p.m., NBC).

• The hunt for Jekyll puts several team members at risk on “CSI” (8 p.m., CBS).

• Changes take place in both parallel worlds on “Fringe” (8 p.m., Fox).

• Demi Moore, Tracy Morgan and Jim Breuer join “The Marriage Ref” (9 p.m., NBC).