Gustavo Santaolalla, the music composer for video games The Last of Us (2013) and The Last of Us: Part II (2020), was brought on to compose the series soundtrack.
The Mandalorian (2019) producers gave Pedro Pascal permission to work on the series. He is reportedly earning $600,000 per episode, making him one of the highest-paid American television stars.
In the games, the fungus is spreading through spores in the air. For the show, they were replaced with tendrils. Neil Druckmann explained that this was a deliberate decision he made early on during the show's development, as he wanted to make the world more believable and the fungus more frightening.
A non-gamer, Pedro Pascal watched his nephew play the beginning of the first game because he lacked the skill to play it himself; he found Joel to be "so impressive" but was concerned about imitating the games too closely, instead choosing to "create a healthy distance" and allow the showrunners to decide the characterization.
In the first season, Merle Dandridge and Laura Bailey reprised their roles as Marlene and Firefly nurse respectively.