The first cast member of Harry Potter and the Philosopher's Stone was announced on 23rd July, 2000 (Daniel Radcliffe's birthday). It was an owl!

The Owls

There were 12 owls on set in Harry Potter and the Philosophers Stone. There were 6 snowy owls, 2 barn owls, 2 eagle owls, and 2 massive owls! All of the owls had their owl perch in the churchyard of Durham Cathedral - (where they filmed the spooky owls sequence)!

Hedwig

Harry's faithful pet was played by 2 owls, Gizmo and Sprout. Gizmo was the main owl, and she did all of the stunts. Experts say that Sprout is a male owl so Hedwig keeps changing gender throughout the film.

The Great Hall Sequence

The Great Hall sequence when Hedwig flys in with Harry's Nimbus 2000 was filmed in a very cunning way. 

Gizmo had been trained for 6 months to allow her to be able to pull-off this stunt. The broomstick, which weighed about 60 grams, was attached to Gizmo on a rig allowing them to release it at the last minute so that it fell onto Harry's plate.

There were 12 cats used in Harry Potter and the Philosophers Stone. 4 of them belonged to Sue Wood who trains animals for films. Her cats have also appeared in Cat food advertisements, among other things.

Each of the cats had their own room with a fur-lined basket to go to sleep in inside a Cat Hotel!

The Mastiffs

Fluffy and Fang

3 big, (but not quite as enormous as) mastiffs were used to portray Fang, Hagrid's boarhound and Fluffy, Hagrid's 3-headed-dog which guards the trapdoor on the 3rd floor corridor. They were very noisy and trying to get them to calm down to act with the children was a struggle!

The toads didn't really take a lot of training. You just had to keep an eye on them and watch where they jump!

The rats, on the other hand, were a lot cleverer than the toads and it took some eagle-eyed people to watch where they went!

Scabbers

Ron and Scabbers in Harry Potter and the Philosophers Stone

Scabbers, Ron's pet rat, was an animatronic, which generally means that he wasn't a real rat! This is helpful for a number of reasons:

1) He won't run away

2) He won't die

3) They can make him look like how they want Peter Pettigrew to look so that, in the film of Harry Potter and the Prisoner of Azkaban, Scabbers turns into Pettigrew, they can make them look similar

4) In Harry Potter and the Prisoner of Azkaban at the beginning they can make him look ropey!

5) In Harry Potter and the Prisoner of Azkaban, if Crookshanks gets a bit rough it doesn't matter