Benjamin Schiff Platt (born September 24, 1993) is an American actor and singer. The son of film and theater producer Marc Platt and philanthropist Julie Platt, he began his acting career in musical theater as a child and appeared in productions of The Sound of Music (2006) and The Book of Mormon (2012–2015), rising to prominence for originating the title role in the Broadway coming-of-age musical Dear Evan Hansen (2015–2017). His performance in the latter earned him multiple accolades, including the Tony Award for Best Leading Actor in a Musical (making him the youngest solo recipient of the award at the time), a Daytime Emmy, and a Grammy Award. Platt reprised the role of Evan Hansen in the 2021 film adaptation of the musical, produced by his father. His portrayal of Leo Frank in the 2023 Broadway revival of Parade earned him nominations for a Tony and a Grammy.

Platt's film credits include the Pitch Perfect film series (2012–2017), Ricki and the Flash (2015), Run This Town (2019), and Theater Camp (2023), the latter of which he also co-wrote. Since 2019, he has starred in the Netflix comedy-drama series The Politician, for which he was nominated for a Golden Globe Award.

Platt signed with Atlantic Records in 2017 and released his debut studio album Sing to Me Instead in March 2019. In May 2020, the concert film Ben Platt Live from Radio City Music Hall debuted on Netflix. Platt's second studio album Reverie was released on August 13, 2021. After signing with Interscope in 2023, Platt's third studio album Honeymind was released on May 31, 2024.

In 2017, Platt was included on the annual Time 100 list of the most influential people in the world.

Platt was born in Los Angeles, the fourth of five children of Julie and Marc Platt. His father is a film, television, and theater producer whose credits include Legally Blonde, Into the Woods, La La Land, Mary Poppins Returns, the musical Wicked, and its film adaptation. He has two sisters and two brothers, including actor Jonah Platt. He and his family are Jewish.

He attended the Adderley School for Performing Arts in Pacific Palisades, performing in productions like Bye Bye Birdie and Into the Woods. Platt attended Harvard-Westlake School in Los Angeles, graduating in 2011. He then enrolled at Columbia University in New York but dropped out after seven weeks to fulfill his contract with The Book of Mormon. During his time at Columbia, he was a member of the campus a cappella musical group Nonsequitur.

At 9 years old, Platt played Winthrop Paroo in The Music Man at the Hollywood Bowl alongside Kristin Chenoweth. At 11, he appeared in a brief national tour of Caroline, or Change, by Jeanine Tesori and Tony Kushner. At 17, he played Jean Valjean in Kidz Theater's production of Les Misérables. His other early roles include the role of Claude Bukowski in Columbia University's production of Hair: The American Tribal Love-Rock Musical. He has also collaborated on a workshop of Alice by Heart, by Duncan Sheik and Steven Sater, a new take on Alice's Adventures in Wonderland.

In 2012, Platt was cast as Elder Arnold Cunningham in the Chicago production of The Book of Mormon. The show premiered at the Bank of America Theatre on December 19, 2012, after a week of previews. The production was well received and closed on October 6, 2013. Critics lauded Platt's performance, calling him a "true revelation in this brand new Chicago production... He really leans into this part, throwing himself out there with the abandonment of youth". Platt later reprised his role as Elder Cunningham on Broadway at the Eugene O'Neill Theatre from January 7, 2014, to January 6, 2015.