This one is simply my favorite anime ever.
Plot:
After the invasion of Japan by the Brittannian Empire, the country is renamed to "Area 11". The young Lelouch, a Brittannian student living in Japan, accidentally gets caught up in a local terrorist attack against Brittannia, reuniting with his childhood friend Suzaku as well as meeting the mysterious girl C.C. Cornered in a life and death situation, Lelouch accepts a power C.C. offers to him, the ability to order anyone to do anything. Harboring a thirst for revenge against the Brittanian Empire for their actions against his family, Lelouch wages war against the Empire. Using his newfound power and tactical ability, Lelouch goes under the alias Zero in attempts to fulfill his childhood vow, to destroy Brittannia!
The anime consists of two seasons, which I found to be very addictive and entertaining. This is the kind of anime that you can't wait to see the next episode, and most episodes surprise you at the end. Lelouch is a very complex character, very similar to Light (Death Note) with the diffeence that he never loses his mind to sacrifice his friends or even relatives.
The show also includes mechas, and has a great animation. The fights are addictive to watch. Due to massive liking by everyone, a lot of people just jump on the bandwagon to hate this anime, with no clear arguments. I advice anybody not to do so here.