Aidan Gallagher is an American actor. His first major role was portraying one of the quadruplets, Nicky Harper, in the Nickelodeon comedy television series Nicky, Ricky, Dicky & Dawn. In 2019, Gallagher began portraying Number Five in the Netflix series The Umbrella Academy, which is his breakthrough role and has brought him widespread recognition.

Nicky Harper, the title character on the successful Nickelodeon series Nicky, Ricky, Dicky & Dawn, was cast. He made an appearance on Nickelodeon's Ho Ho Holiday Special in 2015. He went on to star in the Netflix series The Umbrella Academy. Season three of the sitcom began filming in early 2021. He's also a singer-songwriter, with the self-produced tracks "I LOVE YOU" and "FOR YOU" to his credit. He was the youngest solo artist to perform at South by Southwest 2020's Big Break Accelerator Program Showcase, making him the youngest solo artist to participate at the music festival.