Declan Patrick MacManus (born 25 August 1954), better known by his stage name Elvis Costello, is an English singer, songwriter, record producer, author and television host. According to Rolling Stone, Costello "reinvigorated the literate, lyrical traditions of Bob Dylan and Van Morrison with the raw energy and sass that were principal ethics of punk", noting the "construction of his songs, which set densely layered wordplay in an ever-expanding repertoire of styles." His first album, My Aim Is True (1977), is widely regarded as one of the best debuts in popular music history. It spawned no hit singles, but contains some of Costello's best-known songs, including the ballad "Alison". Costello's next two albums, This Year's Model (1978) and Armed Forces (1979), recorded with his backing band the Attractions, helped define the new wave genre. From late 1977 until early 1980, each of the eight singles he released reached the UK Top 30. His biggest hit single, "Oliver's Army" (1979), sold more than 500,000 copies in Britain. He has had more modest commercial success in the US, but has earned much critical praise. From 1977 until the early 2000s, Costello's albums regularly ranked high on the Village Voice Pazz & Jop critics' poll, with This Year's Model and Imperial Bedroom (1982) voted the best album of their respective years. His biggest US hit single, "Veronica" (1989), reached number 19 on the Billboard Hot 100.

Born into a musical family, Costello was raised with knowledge and appreciation of a wide range of musical styles and an insider's view of the music business. His opportunity to begin a professional career as a musician coincided with the rise of punk rock in England. The primitivism brought into fashion by punk led Costello to disguise his musical savvy at the beginning of his career, but his stylistic range has come to encompass R&B, country, jazz, baroque pop, Tin Pan Alley and classical music. He has released album-length collaborations with the classical ensemble The Brodsky Quartet, the New Orleans R&B songwriter and producer Allen Toussaint and the hip-hop group The Roots. Costello has written more than a dozen songs with Paul McCartney and had a long-running songwriting partnership with Burt Bacharach.

Costello has had hits with covers of songs, including Sam & Dave's "I Can't Stand Up for Falling Down", Jerry Chesnut's "Good Year for the Roses" and Charles Aznavour's "She". One of the songs he is best known for, "(What's So Funny 'Bout) Peace, Love, and Understanding", was written by Nick Lowe and recorded by Lowe's group Brinsley Schwarz in 1974, but remained obscure until Costello released his version in 1979. Costello's own songs have been recorded by artists including Linda Ronstadt, George Jones, Roy Orbison, Johnny Cash, Dave Edmunds, Chet Baker and Alison Krauss.

Costello has won two Grammy awards, two Ivor Novello awards, four Edison awards, an MTV Video Music Award, a BAFTA award, an ASCAP Founders award and a Gemini award. In 2003, he was inducted into the Rock and Roll Hall of Fame. In 2016, he was inducted into the Songwriters Hall of Fame. From 2008 to 2010, he hosted a television show, Spectacle: Elvis Costello with..., on which he interviewed other musicians. In 2015, he published a well-received memoir, Unfaithful Music & Disappearing Ink.