Back in August of last year, Geoff Johns confirmed that we'll get to see an Aquaman animated movie, and then at the recent premiere for Justice League: War it was confirmed that an Aquaman animated movie is in development.
The Justice League: War post-credit scene (watch it below) also tied directly into the Aquaman movie as it showed Orm, Aquaman’s brother, carrying a dead old man following Apokolips’ attack on Earth. Orm, or Ocean Master, than said, "The Surface Dwellers have killed our king. This is an act of war. And they will pay."
Now Newsarama has some details about the new Aquaman animated movie as they state the movie will be an origin story for Aquaman based on the New 52 comics, meaning he won’t know much about his connection to Atlantis, his place in their royal family, and his destiny to be their king.
It's also said that Sam Witwer of Being Human will be the voice of Orm.