The 67-year-old Bourne Ultimatum actor will play Donald Rumsfeld opposite Josh Brolin's George W. Bush.
Rumsfeld was twice appointed as the US Secretary of Defence, first for President Gerald Ford in 1975 and later in 2001 for Bush. He resigned in 2006 amid rumours that the President had asked him to step down so the administration could implement a plan to escalate the war in Iraq.
Glenn has also appeared in The Right Stuff, The Hunt for Red October, Training Day and Silence of the Lambs.
Elizabeth Banks, Ioan Gruffudd, Thandie Newton, Jeffrey Wright, Ellen Burstyn, James Cromwell and Rob Corddry are also among the W cast.