Fast National ratings for Thursday, December 15, 2011.
 
Led by new episodes of "Person of Interest" and "The Mentalist," CBS comfortably won Thursday night facing either repeats or viewer-shunned offerings like ABC's Katie Couric special or NBC's "Prime Suspect."
 
Among adults 18-49, CBS averaged a 2.8 rating for the night, topping FOX's 2.2 rating in the key demographic. ABC was third with a 1.6 rating, doubling up NBC's 0.8 rating. The CW averaged a 0.3 rating in the key demo.
 
Overall, CBS averaged nearly 11.9 million viewers and a 7.4 rating/12 share for Thursday primetime. FOX was a distant second with a 4.7/7 and 7.54 million viewers, still way ahead of ABC's 3.7/6 and 5.81 million viewers. NBC's 1.8/3 and 2.63 million viewers still bettered the 0.7/1 and 945,000 viewers for The CW.
 
[Univision averaged 3.46 million viewers and a 1.4 rating among adults 18-49 for Thursday primetime.]
 
8 p.m. - The 8 p.m. block was the only hour that featured any real competition on Thursday. CBS finished first overall and a close second among adults 18-49 with a "Big Bang Theory" repeat (10.145 million viewers and a 2.8 key demo) and a new "Rules of Engagement" (9.71 million viewers and a 2.7 key demo). FOX's "The X Factor" averaged 9.65 million viewers for second overall and won the hour with a 2.8 (or even 2.85) key demo rating, though both numbers represented declines from recent results episodes. ABC's "A Charlie Brown Christmas" was third with 6.405 million viewers and a 1.8 key demo rating. NBC's repeats of "Community" and "Parks & Recreation" averaged 2.05 million viewers and a 0.7 key demo rating. The CW's "Vampire Diaries" repeat averaged 1.015 million viewers and a 0.3 key demo rating.
 
9 p.m. - CBS moved into a comfortable lead in the 9 p.m. hour with the 12.79 million viewers and 2.8 rating among adults 18-49 for "Person of Interest." ABC's "The Year With Katie Couric" special was a distant second with 5.73 million viewers, edging out the 5.42 million viewers for FOX's "Bones" repeat, while both networks delivered a 1.5 key demo rating. NBC's "The Office" and "Whitney" repeats averaged only 2.23 million viewers and a 0.9 rating, again staying ahead of only The CW's repeat of "Secret Circle," which averaged 874,000 viewers and a 0.3 key demo rating.
 
10 p.m. - "The Mentalist" capped CBS' primetime win with 12.98 million viewers and a 2.7 rating among adults 18-49 for the 10 p.m. hour. ABC's Katie Couric special slipped to 5.31 million viewers and a 1.4 key demo rating in its second hour. And on NBC, a new episode of "Prime Suspect" drew only 3.62 million viewers and a 0.8 key demo rating.
 
All ratings information comes from preliminary Fast National Nielsen data, which includes live and same-day DVR viewing. All numbers are subject to change.