Straight from the Source.

Koos Van Den Akker and Bill Cosby

Koos was responsible for kick- starting the Cosby sweater trend of the 1980's. He was asked by a close mutual friend of Cosby's to design a sweater for him, according to his site, the rest is history.
"[Josephine Premice] took it to the set of the Cosby Show where Bill immediately put it on and wore it for the taping. It was an instantaneous hit. Cosby, in his incredibly generous way began giving his friends presents made by Koos left right and center and the Koos designs became a sensation".
Along with other notable companies such as the wild Australian brand Coogi, the trend rode out the rest of the 80's and early 90's and is currently experiencing a resurgence among the hipper more ironic kids out there. America being the land of kitsch, it's not surprising to see younger generations embracing their poly-blend nits with gusto these days!
Leoxoxo