CBS finished first among the four major broadcast networks on the opening night of the 2014-15 prime-time television season, with two episodes of its comedy “The Big Bang Theory” the night’s most-watched programs.

Of Monday’s three series premieres, the CBS drama “Scorpion” drew the most viewers, averaging 13.83 million viewers from 9-10 p.m., following the two episodes of “The Big Bang Theory,” which averaged 18.03 million and 18.24 million, according to live-plus-same-day figures released by Nielsen today.

The premiere of Fox’s Batman origin series “Gotham” averaged 8.21 million viewers from 8-9 p.m., against “The Big Bang Theory,” the NBC singing competition “The Voice,” and ABC’s “Dancing with the Stars.”

The other premiere, the ABC drama “Forever,” averaged 8.59 million viewers from 10-11 p.m.

Ratings for premieres are often unrepresentative of how the series will fare due to the heavy promotion they receive and because viewers who are interested in the concept may not return for future episodes.

CBS averaged 13.19 million viewers for the night. NBC was second, averaging 12.75 million, followed by ABC, which averaged 11.39 million and Fox, which averaged 6.86 million.

NBC finished first among four major networks among viewers ages 18-49, the group ABC, Fox and NBC target and advertisers covet because it watches less television and is harder to reach.

ABC, CBS and NBC broadcast three hours of prime-time programming for ratings purposes Monday and Fox two hours.

NBC also led among viewers ages 18-34, 12-17 and 2-11. ABC and CBS tied for first among viewers 50 and older, a group long dominated by CBS.