Each sentence describes a “crime” for which its perpetrator was beheaded. Appropriately, every word in the sentence has itself been “beheaded” by having the first letter removed.

The unaltered descriptions, with their answers, are:

• Sheltered a Christian priest = Saint ALBAN
• Killed his party guest with a piece of birch firewood = Tahvo PUTKONEN
• Turned people to stone = MEDUSA
• Sold adulterated tobacco = Antoine LAVOISIER
• Tried to kill a crew member with a magazine = ASH (android from Alien)
• Distributed anti-war leaflets with his sister Sophie = Hans SCHOLL
• Rebuked Herod for marrying Herodias = JOHN THE BAPTIST
• Committed treason by naming Stannis as heir = Eddard STARK
• Was about to destroy Bethulia = HOLOFERNES
• Was posthumously convicted of the regicide that made him Lord Protector = Oliver CROMWELL
• Led peasant uprising of 1525 = Thomas MÜNTZER
• As a monk, opposed Ieyasu in 1600 = Ankokuji EKEI
• Fought Mace Windu in the Battle of Geonosis = Jango FETT

The answer names must themselves be beheaded to acrostically spell out LUE ASCOT OR UKE, which is itself a beheaded clue: BLUE MASCOT FOR DUKE. Duke’s mascot is the Blue DEVIL.

Beheading DEVIL gives the answer: EVIL.