CBS’ “The Big Bang Theory” and ABC’s “Scandal” remained the hottest shows on Thursday this week, ranking as the top draws among young adults as the nets tied for the demo lead. ABC helped its cause by airing a special “Shark Tank” leading off the night.

According to preliminary national estimates from Nielsen, “The Big Bang Theory” (4.6 rating/7 share in adults 18-49, 16.0 million viewers overall) was easily Thursday’s top program in all key categories, dipping from last week’s return after a break for college basketball. “The Millers” fell off from there (2.6/9 in 18-49, 10.2 million viewers overall) but led its timeslot as well, and “Two and a Half Men” (2.4/8 in 18-49, 9.6 million viewers overall) was down slightly from last week and ranked first or second in its timeslot in all categories.

The Crazy Ones” was the only CBS comedy to hold at last week’s demo level (and was up slightly in total viewers), as an episode reuniting “Mork & Mindy” co-stars Robin Williams and Pam Dawber averaged a 1.7/5 in 18-49 and 6.9 million total viewers; its season finale is set for next week. Closing the night for the Eye, “Elementary” (1.7/5 in 18-49, 7.9 million viewers overall)

For the night, CBS led in adults 18-49 (tie), 25-54 and total viewers.

Elsewhere, ABC opened with a special off-night original episode of “Shark Tank” (1.6/6 in 18-49, 6.6 million viewers overall), down from its usual average on the less-competitive night but good enough for second place in 18-49 for the hour — doubling the 0.8 of last week’s finale for “Once Upon a Time in Wonderland.”

“Grey’s Anatomy” (2.5/8 in 18-49, 8.1 million viewers overall) was down a bit from last week but won at 9 p.m. in young adults, and “Scandal” was up a little (3.0/9 in 18-49, 9.1 million viewers overall) and will finish the week as the No. 1 broadcast drama in adults 18-49. “Scandal” wraps its season next week.

At Fox, “Hell’s Kitchen” was affected by the additional reality-show competition in the 8 o’clock hour from “Shark Tank,” sliding 18% (0.3) week-to-week and placing third for the hour. Despite that lower lead-in, “American Idol” (1.7/5 in 18-49, 7.5 million viewers overall) and “Surviving Jack” (1.2/4 in 18-49, 4.3 million viewers overall) held steady. The stability of “Jack” is a good sign, and bodes well for its renewal chances.

It was another sluggish Thursday for NBC, where new episodes of “Community” (0.8/4 in 18-49, 2.6 million viewers overall), “Parks and Recreation” (1.0/4 in 18-49, 2.6 million viewers overall) and “Parenthood” (1.0/4 in 18-49, 3.6 million viewers overall) were all down a tenth from last week. At 9 p.m., a repeat of “Hollywood Game Night” did a 0.7/2 in 18-49 and 2.7 million viewers overall.

At CW, “Reign” (0.4/1 in 18-49, 1.2 million viewers overall) built a bit on its repeat “Vampire Diaries” lead-in (0.3/1 in 18-49, 1.2 million viewers overall).

Preliminary 18-49 averages for the night: ABC and CBS, 2.4/8; Fox, 1.4/5; NBC and Univision, 1.0/3; CW and Telemundo, 0.4/1.

In total viewers: CBS, 9.8 million; ABC, 7.9 million; Fox, 5.0 million; Univision, 2.6 million; Telemundo, 1.1 million; CW, 1.0 million.