There are at least three groups named Sweet William:
1. A german Indie/Alternative Band formed in 1986 in Kerpen near Cologne(Koeln), by Singer and guitarist Oliver Heuer, bassist Bodo Rossner,drummer Marius Nage and guitarist Thomas Grahl. First EP: "To Have a Relapse“ 1990 on Big Noise Records. Later they signed to Hyperium/Rough Trade Records and Dion Fortune.
Since 2001 they released 11 albums on their own.
They early music was a blend of New Wave, Punk and Gothic Rock, but by the time their style was more like psychedelic and electro rock.
Actual LineUp is:
Oliver Heuer, Singer
Marcus Gerlach, drums, percussions
Frank Breuer, bass

2. Formed in Adelaide, Australia in 1995, the indie-pop quartet Sweet William comprised singer/guitarist Jason Sweeney, guitarist Louey Hart, bassist Karl Melvin and cellist Allye Sinclair. Complete with a drum machine dubbed Dr. Rhythm, the group debuted on the Apocalypse of Boredom compilation, also issuing a single on the Matinee label before releasing the EP Ambiguous on Twee Kitten in 1998. The mini-album World of Books followed the next year, on American label Shelflife. After this Jason went on to record as Simpático and found a home on Matinée. He also plays using other names like Other Peoples Children, Pretty Boy Crossover and School of Two.

3. A bluegrass (with a tinge of rock) group based in New York.

4. A gothic rock group.

5. A beatmaker from Japan Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.