Age: Unknown
Birthday: Unknown
Height: Unknown
Role in AC: Flashback, Appears at End
Role in FFVII: Flashback
Zack was a SOLDIER 1st class who gave his life to save Cloud. After the two escaped from the Shin-Ra Mansion Basement, they were caught up with just outside of Midgar. Zack was shot trying to save Cloud. Cloud managed to escape, taking Zack's Buster Sword as his weapon.
After the events of FFVII, Cloud returned to the place where Zack was shot and placed Zack's Buster Sword in the ground as a memorial. A wolf can be seen around this area, which is speculated to be the spirit of Zack.
Zack's role in Advent Children is mainly limited to flashbacks and which indicate Cloud's inspiration that he takes from Zack. However at the end of the film, Zack is seen with Aerith as the two look over the happy Cloud.
Age: Unknown, 2000 years+
Birthday: Unknown
Height: Unknown
Role in AC: Flashbacks, key part of storyline
Role in FFVII: Enemy, multiple bosses
Jenova was originally discovered by Shin-Ra in a geological stratum. Thought to be one of the Ancients, Jenova is actually a creature from outer space who had traveled the galaxy in search of worlds to destroy and infect, before moving onto the next. It was in fact the Ancients who did manage to trap her, which was where she lay until she was discovered 2000 years later.
Shin-Ra ultimately used Jenova's cells for multitudes of experiments in trying to create the ultimate SOLDIER. One of these people was Sephiroth who was injected with Jenova cells before he was born. When Sephiroth found out about these experiments, he believed that Jenova was his real mother and planned to fulfill her legacy by destroying the planet.
Although Jenova is not physically in the film [unless you include the box that her remains are held in], she plays a very important role. For it is Jenova who is 'Mother' who Kadaj, Loz and Yazoo are searching for. Jenova is the key to the Reunion and the key for Sephiroth's return.
Shadowcreepers are creatures who can be summoned by Kadaj who appear to materialize [and dematerialize] out of clouds of thick black smoke.
The creatures usually appear in packs, attacking with their teeth or claws. They are around the size of a jungle cat, although they appear to have a more scaly, reptilian skin and a head that resembles a dragon-type.
They appear twice in the movie. At the beginning when Cloud is attacked outside Midgar. And before Bahamut Sin is summoned, when they are used to move the crowd away from the Meteor Monument.
In the tradition of Final Fantasy VII [and all Final Fantasies], the great summon creature Bahamut makes a return in Advent Children.
This manifestation, known as Bahamut Sin is summoned by Kadaj after he gains the use of the groups materia and by using the children he has manipulated.
Kadaj summons the creature initially to destroy the Meteor Monument where he believes that the remains of 'Mother' are buried after Loz and Yazoo have no luck in pulling it down. However, when nothing is found, the creature continues to rage havoc upon Edge when Rufus Shinra does not tell him what he needs to know regarding the true location of 'Mother'. Bahamut Sin ravages down on the city, taking innocent lives along with doing damage.
Bahamut is ultimately defeated by Cloud, after a battle with the original party members from FFVII. He is able to reach the beast far up in the sky through the help of his friends.
