Sunday’s deadly episode scores a whopping 12.4 million total viewers and 8.1 in the 18-49 demographic, both series bests.

AMC’s The Walking Dead remains unstoppable.

Sunday’s deadly season-three finale shattered the zombie drama’s own ratings record yet again, scoring 12.4 million total viewers in its initial 9 p.m. broadcast and 8.1 million in the advertiser-coveted adults 18-49 demographic. The numbers represent series bests in total viewers and the demo.

The ratings for the finale — which (spoiler alert) was the end of the line for series regular Laurie Holden (Andrea) — mark a drastic improvement compared with Walking Dead‘s second-season finale in March 2012. That episode, which marked the deaths of recurring characters Jimmy and Patricia, scored 9 million total viewers and 6 million in adults 18-49 and 5.3 in 25-54, the latter a then-record.

The final episode overseen by departing showrunner Glen Mazzara also bested February’s season three midseason premiere, which scored 12.3 million total viewers and 6.7 million in 25-54 — both bests at the time.

The numbers for the series based on Robert Kirkman‘s comics become more impressive when factoring in heavy competition from HBO’s season-three premiere of Game of Thrones and the finale of History’s miniseries The Bible — as well as typically decreased viewership levels on Easter Sunday. For its part, Game of Thrones also notched a series high, with Sunday’s season kickoff drawing 4.4 million total viewers in its initial 9 p.m. broadcast.

“Two words: Grateful. Dead,” AMC president Charlie Collier said. “It’s a joy that we get to work with such tremendous talent to make The Walking Dead and Talking Dead come to life for audiences that continue to engage and grow. In just three seasons, The Walking Dead has become a pop-culture phenomenon, entertaining millions of passionate viewers and obliterating traditional lines between cable and broadcast television.”

Sunday’s finale also ranked as the No. 1 program for the night across cable and broadcast television among adults 18-49, with its live wrap-up show The Talking Dead topping Game of Thrones in total viewers afterward. The 9 p.m. broadcast of Walking Dead was up 38 percent year-over-year versus the season-two finale and up 26 percent in 18-49. Among adults 25-54, Sunday’s conclusion drew 7 million total viewers, up 31 percent year-over-year and another series best. Season to date, Walking Dead ranks as the No. 1 show on TV — broadcast or cable — among 18-49, averaging 5.6 million viewers.

Meanwhile, Sunday’s Chris Hardwick-hosted Talking Dead finale — which was expanded in February to an hour — also was up considerably from its midseason return. The talk show pulled in 5.2 million total viewers at 10 p.m., up considerably from the 4.1 million who watched in February and a series best.

Some ratings highlights from The Walking Dead:

• Season 3 finale, March 31: 12.4 million total viewers*, 8.1 million in 18-49*, 7 million in 25-54*

• Season 3 midseason premiere, Feb. 10: 12.3 million total viewers*, 6.8 million in 18-49, 6.7 million in 25-54*

• Season 3 midseason finale, Dec. 2: 10.5 million total viewers, 6.9 million in 18-49, 6 million in 25-54

• Season 3 premiere, Oct. 14: 10.9 million total viewers, 7.3 million in 18-49, 6.1 million in 25-54*

• Season 2 finale, March 18, 2012: 9 million total viewers, 6 million in 18-49, 5.3 million in 25-54*

• Season 2 midseason premiere, Feb. 12, 2012: 8.1 million total, 5.4 million* in 18-49, 4.4 million* in 25-54

• Season 2 premiere, Oct. 16, 2011: 7.3 million total, 4.8 million* in 18-49, 4.2 million* in 25-54

• Season 2 midseason finale, Nov. 27, 2011: 6.6 million total, 4.5 million in 18-49, 3.9 million in 25-54

• Season 1 finale, Dec. 5 2010: 6 million total, 4 million in 18-49, 3.5 million in 25-54

• Season 1 premiere, Oct. 31, 2010: 5.4 million total viewers, 2.7 million in 18-49

* Record at the time [HollywoodReporter]