"Greatest" is impossible to define, but if you are interested in authors of critical acclaim and literary quality, a good place to find names would be to look at authors who have won American Literary Awards, such as the National Book Award.
A Wikipedia search of "American literary awards" turns up a comprehensive list.
Some critically acclaimed and frequently studied living authors of American literature include (but are not limited to):
Maya Angelou
John Irving
Joyce Carol Oates
J.D. Salinger
Gore Vidal
Tom Wolfe
and Nobel Prize winner Toni Morrison.
as of 12/17/2009
Cormac McCarthy (b. 1933)
Don Delillo (b. 1936)
Philip Roth (b. 1933)
Thomas Pynchon(b. 1937)
he is living in hendersonville, tn. along with his wife, margie singleton.
Bob Dylan
Yes, one of Bon Jovi's greatest hits in 1986
The most known living classical pianist is Martha Argerich...(according to Grammophon she is the greatest living pianist)
he is the greatest living songwriter influencing almost all songwriter/musicians who came after, the beatles included,and all 4 beatles themselves are on record as saying how much they were influenced by the great man .
What is Americas greatest contribution to world theater
The greatest writer of Latin prose is Cicero
Our children.
he was named after the Americas greatest architect because after his buffalo sculpter he was named after Americas greatest architect
thomas jefferson
Who was Americas greatest ally
A writer and a play-writer
Yes
The precious metals
<a href="http://www.scribd.com/doc/148705995/The-Greatest-Living-Artists-of-2013">Greatest Living Artists of 2013</a>
Francesco Petrarch
die They write...