Stella is a painter, sculptor and printmaker. Back in the 50s when Abstract Expressionism was all the rage? He went against the grain. His work, at the time was more minimalist. He also was noted for using house paint in his paintings, eschewing the "painterly." He is one of the most highly regarded living artists.
To read an interesting interview with Stella go to BOMB Magazine.
Stamos, born in New York, was an early Abstract Expressionist. His work, in the 1950s, was influenced by East Asian art (this includes the painting below). Unfortnately for Stamos he is more remembered for being involved in the defrauding of the Mark Rothko estate than his art. You can read more about him at the Phillips Collection website.
Williams was an abstract painter who often (but not in the piece below) worked with oddly shaped canvas. He was a graduate of the San Francisco Art Institute. He exhibited in New York extensively during the 1960s and 70s. Much of his work is geometric in nature. Sadly he died young, at the age of 53.