Charlie Day is an American actor, writer, and producer who has built a career in both live-action and voice-over work. Born in New York City on February 9, 1976, he is perhaps best known for his long-running role as Charlie Kelly on the FX comedy series It's Always Sunny in Philadelphia, a show he also co-created, writes, and executive produces. His background in comedy and his distinctive, high-energy vocal delivery have translated into a number of prominent voice roles in animated features.

Day's entry into voice acting began with a role in the Pixar film Monsters University in 2013, where he voiced the character Art. This was followed by a significant role as Benny, a nostalgic 1980s-spaceman, in the critically and commercially successful The Lego Movie in 2014, a part he reprised for its 2019 sequel, The Lego Movie 2: The Second Part. These films marked the beginning of a recurring collaboration with actor Chris Pratt, who voiced the lead roles in both Lego Movie films.

Day's most high-profile voice role to date came in 2023 when he voiced Luigi in Illumination's animated adaptation, The Super Mario Bros. Movie. Cast opposite Chris Pratt as Mario, Day brought his own interpretation to the character of the taller, more timid brother. In interviews, he expressed a personal fondness for Luigi, noting that his older sister always chose to play as Mario when they were children, which led him to appreciate Luigi's character. He drew inspiration for the voice from people he knew in New York and worked closely with the film's directors to realize their vision for the character. His performance was part of an ensemble cast that was widely praised for its energy and comedic timing. Day is scheduled to reprise the role of Luigi in the upcoming sequel, The Super Mario Bros. Movie, and has also been cast in the animated film Wildwood, both slated for release in 2026.

Throughout his voice acting career, Day has demonstrated a recurring professional relationship with actor Chris Pratt. The two have co-starred in The Lego Movie franchise and The Super Mario Bros. Movie, creating a notable pairing in contemporary animated film. While Day's primary acclaim comes from his live-action work and writing—including nominations for a Critics' Choice Television Award and a Satellite Award for his role in It's Always Sunny in Philadelphia—his voice roles have contributed to major box office successes and expanded his reach as a performer in family entertainment.