Harbour beat out Bobby Cannavale (Mr. Robot), Asia Kate Dillon (Billions), Delroy Lindo (The Good Fight), Michael McKean (Better Call Saul) and Peter Dinklage (Game of Thrones).
Harbour won for his role as Hawkins, Indiana Chief of Police Jim Hopper in Stranger Things 2, which sees the one-time father hide away and raise the psionically-gifted Eleven (Millie Bobby Brown). Harbour called it his "great honor" to play the role.
"In Stranger Things this season, Hopper spends the majority of the fall of '84 holed up in a cabin with a maturing young woman, desperately, stumblingly trying to care for her as her ever-adapting, evolving needs slip through his unsophisticated fingers, his rigid beliefs, his fear that the world isn't ready," Harbour said in his acceptance speech.
"She is the key to suturing the wound, resurrecting life, cleansing the infection, closing the rift," Harbour says of Hop's surrogate daughter, Eleven, who stands as the last line of defense between the world and a dimension-crossing creature.
"I'd like to thank my sparring partner, the gifted, the incomparable Millie Bobby Brown," Harbour said, offering thanks to his mother as well as Stranger Things co-star Winona Ryder.
The hit Netflix original series was also nominated for Best Drama Series.
Stranger Things was officially renewed for a third season in December, shortly after the arrival of the sci-fi drama's highly-anticipated second season in October.
The series' young stars, appearing together at last weekend's Golden Globes, "don't know anything" about the upcoming third season. Harbour expects he'll return for season three, but he's "not allowed" to discuss new details.
"They haven't told me anything," Harbour said in December. "I think I'll be in it though, that's all I know."
Harbour hopes season 3 will explore the dynamic between Hopper and Ryder's Joyce Byers, saying he would "love more stuff with her," and wants to appear more alongside Joe Keery's Steve and Gatan Matarazzo's Dustin as well as explore Hopper's backstory.0comments
The actor stars as the eponymous horned hero in Lionsgate's Hellboy reboot, in theaters January 11, 2019.
All episodes of Stranger Things are available for streaming on Netflix.