1. A Good Man Goes To War, Mercifully
The Doctor's grandest act of mercy came in his Eleventh guise at Demon's Run. A kidnapped Amy Pond has given birth to Melody, who The Silence want to nurture into the ultimate weapon to bring down The Doctor in the endless war that rages, at Trenzalore, between The Chruch and The Time Lord that is seen in "The Time of The Doctor" to stop him answering that question "Doctor Who?". Of course, Eleven did not know all of that at this moment of his personal timeline. The Doctor and his team of allies take Demon's Run without any bloodshed. He gets angry at Colonel Manton, telling him to be the soldier that tells the army to runaway in the hope that people will tease him forever with the nickname, Colonel Runaway. At this point, The Doctor addresses his anger and says "I don't know what's going to happen now". Nothing really. Madame Kovarian is able to escape and the Headless Monks start a war on The Doctor's allies (causing two deaths) and they still get away with the baby due to the one "saved" being a flesh duplicate. If only he had shown the ruthlessness, seen at the start, when he wiped out an entire Cybermen battle fleet despite them not being an immediate threat to him. Mercy, Doctor. Too much mercy.