Khan Noonien Singh: First things first, Captain. Kill Admiral Kirk. Clark Terrell: Sir, it is difficult. I... I try to obey, but-- Khan Noonien Singh: Kill him. Clark Terrell: I... Khan Noonien Singh: Kill him, Terrell, now! McCoy: God sakes!

Struggling to escape Khan's brainwashing, Clark Terrell commits suicide. Chekov collapses shortly afterward.