"What I've Done" is a song by American rock band Linkin Park. It was released as the first single from their third studio album, Minutes to Midnight (2007), and is the sixth track. The song was released as a radio single on April 1, 2007, as a digital download on April 2, and as a CD single on April 30. The live version of "What I've Done" from Road to Revolution: Live at Milton Keynes was nominated for Best Hard Rock Performance at the 52nd Grammy Awards, but did not win. It serves as the end credits track of the 2007 science fiction blockbuster film Transformers, also appearing on its soundtrack. Being certified six times platinum by the RIAA, it is the band's most commercially successful single in terms of pure sales, and reached number 7 on the Billboard Hot 100. In January 2025, the song became the fourth by the band to surpass one billion streams on Spotify.
In January 2011, it was released in a Linkin Park DLC pack for Rock Band 3. The song is also a B-side to the UK single of "Iridescent", the theme for Transformers: Dark of the Moon.