Notes

About Code Geass (Warning: Spoilers)

Code Geass: Lelouch of the Rebellion is a popular Japanese anime that ran for 2 seasons. At the end of the second one, the protagonist Lelouch vi Britannia makes the ultimate sacrifice by establishing himself as a cruel tyrant, and then allowing his friend and rival Suzaku to kill him. The world celebrates the death of the evil Emperor, and peace is finally achieved - just like the two of them intended.

The fate of Lelouch, however, isn't so clear. Almost every character in Code Geass believes him to be dead, with the possible exceptions of Jeremiah and C.C. There's no conclusive proof that Lelouch is alive: the anime is open-ended, leaving it up to the watcher to decide - however, there are several hints and some very good arguments to support that. Personally I like to think that Lelouch is very much alive and well, traveling the countryside with his immortal companion C.C. and sampling pizzas and beer around the world. You will find some of the best arguments in favor of this theory below.

Proof That Lelouch Is Alive

DID LELOUCH SURVIVE IN THE END? YES, AND HERE'S WHY!

Nunnaly saw Lelouch's memories when she touched him after he got stabbed by Suzaku/Zero. This is probably the best argument in favor of Lelouch being alive, since there's no other explanation for this weird phenomenon besides Lelouch acquiring Code, and thus gaining immortality, just like C.C.
C.C. has the Code, and you will remember that people saw her memories upon touching her on several occasions. Many years ago, C.C. was a Geass user herself - just like Lelouch - until her powers evolved sufficiently, and she acquired the Code from another Code possessor.

As for where Lelouch would acquire the Code (since he did not take it from C.C.): he got it from his father, Charles, in the World of C. You will recall Charles attacked Lelouch at the very end, and tried to choke him before Lelouch made him disappear.

This would make Lelouch a unique being, possessing both the Geass and the Code. Some people say the hint is the name of the anime itself (Code Geass) - it certainly fits, although that's not a very strong argument.

Jeremiah (aka Orange) didn't attempt to stop Zero (Suzaku) as he attacked Lelouch. He merely pretended to protect him. Furthermore, he even smiled and mentally told Suzaku to go on when he used his shoulder to jump. This is very weird, as Jeremiah was fiercely loyal to Lelouch ever since learning the truth about his mother. Obviously he knew that Lelouch was going to "die" that day, although it's not clear if he knew the full extent of his plan. We could speculate that Orange-kun, being as loyal to Lelouch as he is, would only agree to the plan if he knew Lelouch was going to survive.
The name of the second season, Code Geass R2, might symbolize Lelouch acquiring the Code. As you probably recall, C.C. and other code users are often called "C2", "V2", and so on. Lelouche Lamperouge would logically be called R.R., or R2 (seeing how Japanese pronounce L as R - Engrish FTW!). A weak argument for sure, but worth mentioning nevertheless.
Schneizel continues to serve Zero after Lelouch's supposed "death". Since Lelouch used Geass to force Schneizel to serve Zero (Suzaku in disguise), after his death the effect of Geass should have ended. That Schneizel continues to serve Zero is an indirect proof that Lelouch survived.
C.C. asks Lelouch a direct question at the very end of the Code Geass R2 anime. Another very strong argument, especially in the Japanese version of the Code Geass R2 episode 25, which you can watch below. C.C. asks Lelouch the following:
Geass, the power of the kings, makes people lonely. *laughs* Maybe that's not quite true, after all. Isn't that right, Lelouch?

Some people might claim that she was just talking to herself, but here are two important facts to consider:

a) She definitely raised her voice when asking Lelouch if she was right (this is much more pronounced in the Japanese version with her "nee, Lelouch" being a lot louder than her previous musings).

b) In the uncut Japanese version of episode 25, after C.C. asks the question, the camera switches to show the face of the cart driver, who smirks in a similar manner that Lelouch does. His face is obscured by the hat, but he definitely has the same black hair. (This part was apparently cut out later in the English dub to leave a more ambiguous ending).