The former keyboardist of Swedish progressive death metal band Opeth, and a member of Michael Amott's stoner metal band Spiritual Beggars. Wiberg toured with Opeth from the 2003 Deliverance/Damnation tour onward, and joined Opeth officially in 2005. Wiberg provided backing vocals for Opeth in addition to his keyboard duties. Before joining Spiritual Beggars he was a member of Death Organ, a band based in Borlänge. He has also fronted the band Boom Club, of the same area.