John R. Cash (born J. R. Cash; February 26, 1932 – September 12, 2003) was an American singer, songwriter, musician, and actor. Much of Cash's music contained themes of sorrow, moral tribulation, and redemption, especially in the later stages of his career. He was known for his deep, calm bass-baritone voice, the distinctive sound of his Tennessee Three backing band characterized by train-like chugging guitar rhythms, a rebelliousness coupled with an increasingly somber and humble demeanor, free prison concerts, and a trademark all-black stage wardrobe which earned him the nickname "The Man in Black".

Born to poor cotton farmers in Kingsland, Arkansas, Cash rose to fame in the burgeoning rockabilly scene in Memphis, Tennessee, after four years in the Air Force. He traditionally began his concerts by simply introducing himself, "Hello, I'm Johnny Cash", followed by "Folsom Prison Blues", one of his signature songs. Alongside "Folsom Prison Blues", his other signature songs include "I Walk the Line", "Ring of Fire", "Get Rhythm", and "Man in Black". He also recorded humorous numbers like "One Piece at a Time" and "A Boy Named Sue", a duet with his future wife June called "Jackson" (followed by many further duets after their wedding), and railroad songs such as "Hey, Porter", "Orange Blossom Special", and "Rock Island Line". During the last stage of his career, he covered songs by contemporary rock artists of the time; his most notable covers were "Hurt" by Nine Inch Nails, "Rusty Cage" by Soundgarden and, "Personal Jesus" by Depeche Mode.

Cash is one of the best-selling music artists of all time, having sold more than 90 million records worldwide. His genre-spanning music embraced country, rock and roll, rockabilly, blues, folk, and gospel sounds. This crossover appeal earned him the rare honor of being inducted into the Country Music, Rock and Roll, and Gospel Music Halls of Fame. His music career was dramatised in the 2005 biopic Walk the Line.

Cash was born J. R. Cash in Kingsland, Arkansas, on February 26, 1932, the son of Carrie Cloveree (née Rivers) and Ray Cash. He had three older siblings, named Roy, Margaret Louise, and Jack, and three younger siblings, named Reba, Joanne, and Tommy (who also became a successful country artist). He was primarily of English and Scottish descent. His paternal grandmother also claimed Cherokee ancestry, though a DNA test of Cash's daughter Rosanne found she has no known Native American markers. He traced his Scottish surname to 11th-century Fife after meeting with the then-laird of Falkland, Major Michael Crichton-Stuart. Cash Loch and other locations in Fife bear the name of his family. He is a distant cousin of British Conservative politician Sir William Cash. His mother wanted to name him John and his father preferred to name him Ray, so J. R. ended up being the only compromise they could agree on. When Cash enlisted in the Air Force, he was not permitted to use initials as a first name, so he changed it to John R. Cash. In 1955, when signing with Sun Records, he started using the name Johnny Cash.