Previously announced cast members include Sarah Jones, Jorge Garcia, Jonny Coyne and Jason Butler Harner.
Best known for his work in "Jurassic Park," Neill has also starred in the TV series "Happy Town" and "The Tudors." He is to play the head of a government agency, TVGuide.com said.
"Alcatraz" has been described as being about secrets and the most infamous prison of all time. It follows an FBI team investigating why and how a group of prisoners and guards who disappeared decades earlier reappeared in the present day, media reports have said.