Born as a human boy, Cyber 29 would die prematurely after falling from a great height while playing outside with his sister. Doctor Von Reichter would put his brain into the body of a black panther and renamed Data 7.
Data 7 appears as an ordinary panther but doesn't behave typically for one, due to him being formerly a human being as a child before his death and the transfer of his brain into the body of a panther.
He displays patience, gentleness and is shown as docile when it comes to babysitting Julian. He can also get embarrassed as seen when he pretended to be a meowing kitten to lure out a Fixed Idea and Cybersix teased him.
Data 7 also appears to be dependent on Cybersix for love and attention in the comics, expressing loneliness and sadness when she decides to spend her nights with Lucas. He also displays selflessness such as the time he freely offered Cybersix his own sustenance in a dire situation. And in a touching moment, Cybersix kisses him and stops herself from calling him Data 7 and instead lovingly refers to him as Cyber29.
Data 7 is a panther with shiny black fur, yellow eyes, sharp teeth and in the Animated Series, a scar above one of his eyes, although it's only ever shown in his debut episode.
As a child, he had short dark brown hair and wore a reddish brown shirt and light brown pants, the same kind of tattered clothing as Cybersix at the time.
Sometime after World War II, a scientist known as Doctor Von Reichter had fled into the Brazillian rainforest as a wanted war criminal and there, in August around 1971, he conducted genetic experiments and created the Cyber series, two of whom were Cyber 6 and Cyber 29, who would later be known as Cybersix and Data 7, respectively.
The two children were close and one day, they snuck out of the lab into a field and jungle to play, and while climbing a tree a worker caught them and shouted, startling Cyber 29 and causing him to lose his balance and fall to his death. Von Reichter, not wanting to waste anything, saved Cyber 29's brain and placed it into the body of a regular panther known as Data, and renamed him Data 7 after the procedure, where he was kept locked in a cage as he recovered, and where Cyber 6 often visited him.
After seeing their rebellious nature, Von Reichter ordered for the destruction of the Cybers, save for one who was saved by a black slave and the two escaped to a village. Meanwhile, Data 7 was kept for further experimentation to recondition the docile panther to his primal instincts so he could be used as an instrument of death and fear to be used on his slaves.
For years, Data 7 remained ignorant of his life as Cyber 29 until one day, he happened to be present in a meeting between Von Reichter and a Fixed Idea to find Cybersix. An old and present face photograph of Cybersix was exchanged to help in identifying her, and at the sight of this, Data 7 immediately remembered her and retaliated against his creator and attacked the Fixed Idea, and escaped through the night to a ship headed for the city of Meridiana. There, both Cybersix and Data 7 sensed the other and quickly reunited without conflict, despite both looking different, to now fight together against their creator.
Like all of Von Reichter's creations, Data 7 has sustenance in him and also consumes it through the necks of Fixed Ideas, although it's unknown if he needs it to survive.
Data 7's last prominent appearance is when he is consoling Cybersix in the rain in issue 45.
It is unknown on whether Data 7 makes an appearance in the live-action television series, but based on a review of the show, it seems possible. 
Data 7's history is largely left unexplained in the animated series, although we are given glimpses through flashbacks. Data 7 was formerly known as a human boy named Cyber 29. He and Cyber 6 played in the fields together one day when they saw a single red flower growing on the cliff side, and when Cyber 29 attempted to retrieve it for his sister, the cliff gave out and he fell to his death. Von Reichter would later revive him as Data 7 and set him against Cybersix as adults. Although Data 7 suffered amnesia, it was evident he never completely forgot his former life as he remembered bits and pieces until eventually recognizing Cybersix is, in fact, his sister. The realization came through in the form of her arm tattoo for Data 7, and for Cybersix, her brother creating a tear on their photograph of Cyber 29 to resemble his own scar on his brow. They happily and tearfully reunite and would stay by each other's side as they fought against Von Reichter and his creations. Data 7 usually sleeps in an underground room next to the subway. It is not known if he needs sustenance to survive.
Upon his first appearence, Data-7 originally considered Cybersix an enemy. However it wasn't long until he sensed some familiarity between them through glimpses of his past. It wasn't until, Cybersix yelled "29!" upon Julian's fall, that Data-7 fully remembered his long lost sister. Once Cybersix recognized him as her brother, they became companions ever since.
Data-7 first met Julian, when the latter's boss got muscled in by Jose's gang. When Julian almost fell and Cybersix mistakenly shouted "29!" that Data-7 got his memory of his past life as Cyber-29 back. He promptly rescued Julian and ever since has never left Cybersix and in turn became fast friends with Julian acting like the silent older brother figure to him. When Cybersix assigns Data-7 to watch over Julian, he makes sure he never leaves his boat home. Prompting Julian to rely on his cat's cradle trick to intrigue and fool the large panther. While Data-7 would never hurt Julian, he's not above using his natural growl to intimidate him into compliance.
- In the animated series, Data 7's scar is sometimes shown as above and below his brow.
- In Episode 7, Data 7 whines like a dog when Julian outsmarts him.
- In the animated series, Data 7 sleeps in the sewers while in the comic he sleep with Cybersix in her apartment.
- In the comic, all of Von Reichter's creations can sense the other, but it's suggested Data 7 and Cybersix have a stronger connection to each other to what sounds like love and is what helps them quickly find the other, even when they're a considerable distance from the other and changed in appearance after all those years, though this is only touched upon once.
- It is suggested the Cybers are all clones and so share the same biological parents, the father is Von Reichter while the woman is unknown although she was an acrobat.
- Data-7 is a black panther, specifically panthera pardus, or leopard.