The manga artist, Hajime Isayama, got the idea for the Titans when he encountered a drunk customer at a coffee shop he worked in. He was inspired by the inability to communicate and realised the most dangerous thing was the human race.
The Attack on Titan manga sold over 8 million copies in 2014 dethroning One Piece for the top selling Japanese manga of all time.
The name Eren is of cultural ethnic Turkish origin. Its exact meaning and description is "He who progresses/has reached towards divine maturity and sacred wisdom". It can also be interpreted as a "saint" or "holy person".
In the anime, the character, Hange Zoe, is voiced by a woman. However, in the manga, Hange's gender is unknown to the reader. This is because the writer, Hajime Isayama, felt that Hange's gender didn't matter to the story line and left it up to the reader to decide.
Jean Kirschtein is Hajime Isayama's favorite character, because he says what he wants and doesn't worry about what others think.
Mikasa is the only character who is Asian. She is Japanese European, her mother being Japanese and her father being European.
In 2009 Hajime Isayama wrote entries of Attack on Titan manga into a Japanese newspaper. From then on it became very popular and he started writing the series in 2011.
There are a lot of small differences in the anime and manga. There are many name changes due to translations. For example, Eren's mother's name is changed from Kalura to Carla. Another change would be Eren's coloring. Originally his eyes were grey in the manga and in the anime they have been changed to green.
The character Moses had his name changed from Braun, most likely to avoid confusion with Reinier as Braun is also his surname.
The show's protaganist Eren Jaegar's (or Jäger's) name in english would be Eren Hunter.
Levi is 5'3 and is the second shortest male character so far. The shortest male so far is Connie, being 5'2.
In an interview Hajime Isayama made fun of the character Armin Arlert by saying that Armin was a girl.
The English voice actor for Eren Jaeger, Bryce Papenbrook, also voices Kazuto (Kirito) from Sword Art Online. The Japanese voice actor, Yuki Kaji, also voices Finnian from Kuroshitsuji in addition to Eren.