James's Animagus form was that of a stag, which earned him his nickname,
Lily was an animagus too, when Voldemort attacked, she transformed in front of him so that she could attempt to escape. Voldemort hit her with a spell which locked her in her form as a twisted way of leaving her alive for Snape. Harry never noticed but there was always an animal watching him as he grew up.
There's no evidence for or against her knowing.
“A creature I wouldn't want to kiss . . . a spider!” Harry figures out the riddle, and realizes that a spider is about to attack. But what he doesn't realize is what I now believe: that the spider in the maze is Professor Snape, in his Animagus form. It is Spider/Snape who bears down on Cedric and Harry.
In Harry Potter and the Prisoner of Azkaban, Remus Lupin shared that it took his fellow Marauders – James, Sirius and Peter – until their fifth year at Hogwarts to finally become Animagi and keep him company in his werewolf form.
“Technically, it's a ferret.” Barty Crouch Jr. may have been completely wrong to transfigure Draco as a punishment, but he was within the same family of what I believe Draco's Animagus form would take, which is the stoat, or ermine.
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. After all, they are some of the most unique characters in all of Harry Potter.
Peter Pettigrew's Animagus form was a rat. Colloquially, a "rat" is a snitch or informant. Webster's also lists the following possible definition: "a contemptible person: such as... one who betrays or deserts friends or associates."
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.
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.
Snape definitely knew that Sirius was an animagus after PoA since he was in the room while Lupin was telling the story about him becoming a werewolf and how his friends became Animagus. Snape also has the added incentive that he hates Sirius' guts.
Her conscious refusal and readiness to die seals the charm and, thus, Harry's fate as the Boy Who Lived. Although James has the same intention of saving his family while knowing that he is likely to be killed, he is not granted an alternative for his sacrifice to put Lily and Harry under magical protection.
Harry discovers this in Prisoner of Azkaban, when his Patronus turned out to be a stag, his father's Animagus form.
You cannot choose your Animagus animal
But realistically, an Animagus is closely linked to your personality. For example, the brave and rebellious James Potter is famously a stag, whereas the conniving journalist Rita Skeeter is a beetle.
Later on, J.K. Rowling revealed their middle names: Lily Luna and James Sirius, named for Harry's friend Luna Lovegood and his godfather Sirius Black.
Because there was no need for him to become one. Besides he had lot of other important stuff going on in school unlike his father and his friends who were determined to help Lupin.
Madam Professor Minerva McGonagall (born 4 October 1935) was a witch and Animagus who attended Hogwarts School of Witchcraft and Wizardry from 1947 to 1954 and was sorted into Gryffindor.
Falco Aesalon — Falcon; the first recorded Animagus; the registration system was not in existence in his time.
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.
His animagus form is a black cat with a white mark across its chest - a likeness to the small scar Regulus bears after a particularly bad fight he had with Sirius as a child.
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.
Any witch or wizard who wished to become an Animagus had to undergo a ritual-like process in order to achieve the ability. The process of becoming an Animagus was long and difficult and it had to be done in a very specific way, it required skill, practice, and patience.
An animagus (portmanteau of animal and magus) is a witch or wizard who can turn into a particular animal or magical creature at will. This ability is not innate: It must be acquired by magical means.
Also one's Patronus and Animagus forms can be the same. So by that logic it is fairly plausible that Dumbledore's Animagus form could have been a Phoenix.
It hasn't ever been said if it is possible, however, in HP canon, there are no magical creature animagi. There is nothing that says this is impossible, but all known animagi are regular animals.