Tenzin

Tenzin is the son of Aang and Katara in the upcoming series Avatar: Legend of Korra. He is knowledgeable in Airbending, and the new Avatar Korra is searching for him in order to learn from him. Not much is known about Tenzin so far, as Legend of Korra will not come out until 2011.

Rumors & Speculation
These storyline elements remain unconfirmed.
 * His name may be based off of "Tenzin Gyatso", the shortened name given to the Dalai Lama, also part of the name of Aang's master, Gyatso.
 * It is possible that Tenzin could have a personality similar to Gyatso and Aang. However it is unkown what his personality is at this stage.
 * It is also possible that monks are referred to by their last name by other monks of the same level, so Monk Gyatso's first name may have been Tenzin and thus that Tenzin was named after Aang's beloved master.
 * In theory, Korra is the spirtual mother of Tenzin seeing as she is the new Avatar. Since Korra was Aang in the past life, that would technically make her the mother of Tenzin in a spiritual sense.
 * This relationship is similar to how Aang is related to Zuko and Azula (spiritually) due to Aang being Avatar Roku in the past life.
 * It can be presumed that following Tenzin's birth Aang was no longer the Last Airbender while he was alive.
 * It is currently unclear if Tenzin will be the only living Airbender in Avatar: Legend of Korra. He is so far the only one who has been confirmed.
 * The possibility of other Airbenders being alive, in Republic City or the Air Temples, hasn't been ruled out.
 * Furthermore, the possibility of Aang and Katara's having other descendants, also potential Airbenders, has not been ruled out.
 * The marrying age in the Avatar World, at least within the Water Tribe, is 16 (presumably for both parties). Thus as the Legend of Korra is set 75 years after Avatar: The Last Airbender, with Aang having died sometime between 156 and 159ASC, Tenzin's maximum possible age is either 71 or 72.
 * Tenzin being 71 at the oldest seems more likely because Aang was only 12 years old (biologically) at the start of The Last Airbender and only 6 months worth of time is clearly shown to have passed during the series, as both solstices occur within the series.
 * Tenzin is likely to be younger than 71, however as his age has not been confirmed.