Being an animagus wasn't Dark magic, nor particularly useful for ruling over everyone, nor for genocide, nor for achieving immortality, nor for infamy, so Voldy never bothered to become an animagus.
No, Voldemort was not an Animagus. He didn't see any reason to become an Animagus despite being a gifted wizard and knowing a lot of magic. This may simply be because his sole purpose was to obtain immortality and become the strongest wizard who could control the world around him.
Because to process was so difficult and dangerous, and because many witches and wizards simply felt that their time might be better spent in other ways, not many people chose to try becoming an Animagus. Besides that, the skill was of limited practical use anyway, unless one had a great need of disguise or concealment.
Usually people turn into Animagi who match their Patronus, so it is safe to assume Snape would be a doe. But based on his morals qualities, I'd say maybe some kind of prey bird; a crow would be the perfect match.
As a pack animal, or as a “lone wolf,” the wolf is a perfect fit for Harry's Animagus form.
Following both ordeals, Ginny grew into a confident young woman. Her and her friends followed in the footsteps of a previous generation, completely unbeknownst to them, and became Animagi at the age of fourteen, to support their best friend, Maisie Cattermole. Ginny took the form of a grey mare.
Draco is not an animagus in the story. However, if he were to become one, I believe he would be a Siamese cat. His belief in his superiority and his snobbish manner line up with Siamese traits, but he, like the cats, loves his family deeply.
He is seen in his animagus form by Lucius Malfoy while on Platform 9 3/4. Lucius, as a Death Eater, knows about Sirius' animagus form because Peter Pettigrew told the Death Eaters when he returned to their side after book 3.
Extremely intelligent, exceedingly talented and a "wicked" Animagus, it's no wonder Minerva McGonagall is Head of Gryffindor house.
Transfiguration and Animagi are different
For example: if Viktor Krum can transfigure his head into a shark's, like he does in Goblet of Fire, that doesn't mean he is an Animagus. Transfiguration is a form of spell-casting, whereas becoming an Animagus is forever. And yes, he could turn into a falcon. Lucky.
In the Harry Potter books, only a few Animagi (registered and unregistered alike) are even mentioned. They are James Potter, Sirius, Wormtail, Skeeter, McGonagall, Talbott Winger, and an unnamed witch who can turn into a cat. The fact that there are so few Animagi just causes us fans to want to know more about them.
Animagus. Lily's animagus form is a Doe, coupling with her husband, James Potter who is a Stag. Severus Snape's animagus is also a Doe.
In the films, Hermione's Patronus is depicted as a European River Otter, and her Animagus form would most likely be the same animal, as confirmed by author J.K. Rowling.
It is debated (but generally believed possible) for one's Animagus form to be a magical creature, and also debated (but generally believed impossible) for an Animagus to be a dementor.
Falco Aesalon — Falcon; the first recorded Animagus; the registration system was not in existence in his time. Morgan le Fay — Bird; the registration system was not in existence in her time. Minerva McGonagall — Tabby cat; registered. James Potter — Large stag; unregistered.
At the time, he thought Sirius murdered his best friends, and was after Harry. Lupin had to think that it was a possibility that Sirius was transforming in order to evade capture.
He rejected his family's pure-blood elitism and reverence for the Dark Arts. At Hogwarts, rather than be sorted into Slytherin like the rest of his family, Sirius was placed in Gryffindor. In contrast to his home life, Sirius greatly enjoyed life at Hogwarts, where he was inseparable from his best friend, James Potter.
It wasn't Sirius who betrayed the Potters to Voldemort, but he did persuade them to make Pettigrew their Secret-Keeper. It's a choice that ended up tormenting him – so what made Sirius suggest it? We've had a bit of an investigation into why this all happened.
Talbott Winger was a wizard who attended Hogwarts School of Witchcraft and Wizardry in 1984 and was Sorted into Ravenclaw house. He was also an Animagus and took the form of an Eagle.
J.K. Rowling says Draco doesn't have a patronus because he never learned the spell but I think it's because he doesn't have any powerful happy memories to use.
When asked what shape Draco's Patronus Charm is, Rowling replied that, at least by the end of the sixth book, Draco was not capable of producing a Patronus, as it is not magic routinely taught at Hogwarts.
When she completed all the steps, her Animagus form turned out to be a silver tabby cat, with what appeared to be square spectacle markings around the eyes.
Pettigrew's Animagus form was a rat, from which his nickname "Wormtail" was derived. The four friends called themselves the Marauders and designed a map to navigate Hogwarts.
The rare forms include creatures like hippogriffs, unicorns and thestrals, which don't seem like viable Animagus forms. It's not impossible, but it just doesn't seem too plausible that someone could transform into a dragon.