One of my favorite songs of all time, Hallelujah written by Leonard Cohen. I prefer this version to the original, or any of the very many other interpretations. This is a live version performed with a string quartet. Many people will have heard him perform the song on the Shreck movies although he recorded it in 1991 for the Leonard Cohen tribute album "i'm Your Fan".
Classically trained, he studied music at Goldsmiths College, University of London, he moved to the US under the auspice of Aaron Copland in 1963. He worked with John Cage and performed in La Monte Young and Tony Conrad's Theater of Eternal Music before forming the Velvet Underground with Lou Reed in 1965. He left in 1968 and went on to have a very successful solo career. He released Church of Anthrax with Terry Riley in 1971.
He worked with Lou Reed on Songs for Drella, released in 1990, as a tribute to their mentor Andy Warhol. After this, the Velvet Underground re-united briefly in 1993 for a European tour, but the US tour was canceled after Lou Reed and John Cale fell out again!
I am biased here, but I consider Cale to be one of the most original and talented of contemporary musicians along with the likes of Zappa, Prince and John Martyn. Just listen to his version of "Heartbreak Hotel", turning a simple rock & roll song into an emotionally charged epic.
Other suggestions:
"Style It Takes" with Lou Reed.
"Dying on the Vine".
His version of "Venus in Furs" that he first recorded with the Velvet
Underground with Lou Reed on vocals.
"So Long Marianne" with Suzanne Vega on backing vocals.