e-40
i must say, E-40 aka Charlie Hustle or fonzarelli must be one of the least known rappers, yet he has contributed alot to the "hip hop" culture. he has introduced ALOT of slang words that many rappers use nowadays.

he was the first rapper i ever saw, "pop the collars". when someone lifts the collar on their shirt two times 

has introduced words such as "scrilla", "cheddar", "cheese", "broccli", "lettuce" "san yay" "yay area" and a host of other terms that are used by many rappers. hes also been doing the "fo sheezy" rhyming stuff for years, which snoop dog picked up on and started using "fo shizzle" which is trendy nowadays.

he makes up a new word every album. part of the reason he isnt well know because he still is for the most part a california rapper, and his albums mostly circulate in northern california.
"i hope i dont go back to slanging yayo to get my mayo"