Who united England's Anglo-Saxon kingdoms under a single ruler for the first time?

King Æthelstan

In 'Call of Duty: Zombies', what's typically used to barricade doors and windows against zombies? In music, how many notes are there in a standard octave? The River Thames flows through which European capital city? Who was the first female British Prime Minister? Earthrealm and Outworld are realms featured in which legendary fighting game series?