A-positive
From Tardis Wiki, the free Doctor Who reference
A-positive was a very common blood type on Earth.
As of 25 December 2006, about one-third of Earth's population had A-positive blood, including the British Royal Family, Sally Jacobs, Luke Parsons, Geoffrey Baxter, Jason, Alan, Catrin and Jonathan. The Sycorax used this to their advantage in their attempted invasion of the world by using blood control on all the A-positives using a vial of A-positive blood placed on the Guinevere One space probe. (TV: The Christmas Invasion)
