In the UK it was, but it was released in the US in '66. http://en.wikipedia.org/wiki/Sunshine_Superman_%28album%29 "Sunshine Superman is the third album from Scottish singer-songwriter Donovan. It was released in the United States in September of 1966" allmusic.com also has '66 for that album. btw, nobody has mentioned The Byrds Fifth Dimension yet?
Had to go with Simon and Garfunkel but Zappa was a very close second place - I never heard either one do a cut that was bad.
For me it comes close between The Beach Boys 'Pet Sounds' and The Beatles 'Revolver' but it has to be Revolver. Every single track is brilliant and different. Many say Sgt. Pepper is better but I think SP is overated. This is The Beatles masterpiece.