Michael Giacchino (/dʒəˈkiːnoʊ/ jə-KEE-noh; Italian: [dʒakˈkiːno]; born October 10, 1967) is an American film, television, and video game score composer. He has received many accolades for his work, including an Academy Award for Up (2009), an Emmy for Lost (2004), and three Grammy Awards.

Giacchino is known for his collaborations with directors J. J. Abrams, Brad Bird, Matt Reeves, Pete Docter, Colin Trevorrow, Jon Watts, Drew Goddard, J. A. Bayona, The Wachowskis, Taika Waititi, and Thomas Bezucha. His film scores include several films from the Mission: Impossible, Jurassic World, Marvel Cinematic Universe, Star Trek, eight Pixar Animation Studios films, multiple Disney films, Rogue One, The Batman, and several other films. He also composed the score for the video game series Medal of Honor and Call of Duty and the television series Alias, Lost, and Fringe.

In 2018, he ventured into directing, and in 2022 directed the Marvel Studios Disney+ special Werewolf by Night.

Giacchino was born in Riverside Township, New Jersey to an Italian family. His father's ancestors were from Sicily, and his mother's ancestors emigrated from Abruzzo (in southern Italy as well). Giacchino grew up in Edgewater Park Township, New Jersey, and graduated from Holy Cross High School in Delran Township, New Jersey in 1986. He holds dual American and Italian citizenship. His brother Anthony Giacchino is a documentary filmmaker.

Giacchino began combining images and music at age 10, when he began creating stop-motion animation with homemade soundtracks in his basement. While in high school, an art teacher who mentored Giacchino recommended to his parents that he attend the School of Visual Arts in New York City. Giacchino describes visiting the school with his parents thus:

I thought, wow, this is fantastic. They actually have colleges like this? Where I can do the things that I am really interested in doing? That was amazing to me. I loved SVA. I loved the kind of freedom that it provided. It was kind of like this great experiment—okay, you're here because you like something. So let's see how much you like it. We're not going to regulate you too much. We're going to see how passionate and driven you are, and how much you want this thing.

Giacchino enrolled at SVA, majoring in film production and minoring in history. During his final year at SVA, his instructor in film publicity announced an unpaid internship was available at Universal Pictures. Giacchino, who was the only one interested, obtained the six-month position, which he filled at night while attending school during the day and working at Macy's to pay his rent. He graduated from SVA in 1990 with a Bachelor of Fine Arts, after which he took music classes at the Juilliard School, and then at UCLA.

When Giacchino's internship ended, Universal hired him, giving him a job upon graduation from college. He later moved to Disney, and when Disney relocated to Los Angeles, Giacchino moved with them, working in publicity, while taking night classes in instrumentation and orchestration at UCLA. His work for Disney had him interacting with the various personnel who worked in films, such as the producers who hired composers, so when a job at Disney Interactive opened for a producer, Giacchino obtained the job, thinking he could hire himself to write music for the games he produced.