Robert Downey, Jr.
His most recent album is "Prayer Cycle 2: Path to Zero", released in 2011. Guest vocalists this time include Sting, Salif Keita, Rahat Nusrat Fateh Ali Khan, Jonathan Davis of Korn, Jon Anderson, Trudie Styler, Angelique Kidjo, Richard Bona, Yungchen Lhamo, Dadawa, Robert Downey, Jr., Sinéad O'Connor, Serj Tankian, Alex Ebert and, via an archival recording, Jim Morrison.