From Nookipedia, the Animal Crossing wiki
Blathers (フータ, Fūta) is an owl scholar, who first appeared in Dōbutsu no Mori + and has appeared in every Animal Crossing series game since. He is the curator for the museum, and accepts donations such as fish, bugs, fossils and paintings. Blathers can also give the player information on the museum, such as exhibitions, what has been donated and by who. His name comes from the word "blather," which means to babble or speak rapidly without making much sense. He is very knowledgeable and informative, usually giving information on any object donated to the museum, and he will often apologize for his lengthy explanations. As an owl, he sleeps during the daylight hours, but the player can still donate by talking to him and waking him up.
He has a disgust for bugs and always mention it this when a bug is donated to him. He has a sister named Celeste who appears in Animal Crossing: Wild World and Animal Crossing: City Folk, who manages the observatory. Blathers was seen on the cover of Animal Crossing, standing on the roof.
Blathers has a surprisingly detailed history in comparison to many other Animal Crossing characters. As a child, he was brought up in the city, living in his parent's house. After finishing school, he went on to university, completing a number of degrees until reaching the doctorate level. Before he could complete his studies, he was approached by his professor, who recommended that he take up a post in a country museum, as all the curators of the main Faraway Museum refused to move from their posts. Blathers accepted the offer enthusiastically and despite occasional homesickness, he remains at his post. As a result of this move, Blathers still has not finished his doctorate. Blathers is, as confirmed in Wild World, in his mid-twenties.
Due to the museum being added in Dōbutsu no Mori +, and being absent in the original Dōbutsu no Mori, Blathers does not appear until Dōbutsu no Mori +. Blathers tells the player about a correspondence course in fossil identification that he is participating in (he has expressed wishes of being an archaeologist) which he has not completed, meaning that all fossils have to be sent to the Farway Museum to be identified.
He will also accept fish and bugs, which go on show in aquariums and insect exhibits, respectively.
In Animal Crossing: Wild World, Blathers has completed his course in fossil identification and can now identify fossils without having to send them to be identified, giving an immediate result. He still continues to accept fish and bugs, but now accepts paintings which are put up in a painting exhibit. If they are forgeries, he will reject them. His sister, Celeste, is also introduced in Wild World, having an office in the attic of the museum.
Blathers sometimes talks of his encounters with bugs during his studies. He recalls one time in a library, when he opened a book and maggots fell out. He will also mention his fear of cockroaches when one is donated to the museum. If the player donates a bug that has been donated previously, he will reject it and beg the player to keep the cage closed until the player has left the building.
When fish are donated, Blathers usually talks about how the fish tastes, similar to Chip, the host of the fishing tourney.
In Animal Crossing: Wild World, on certain days of the year, Blathers will reveal various background information about himself. These days can be determined easily, as he will be awake for all twenty-four hours of those select days. In addition to his consciousness, he will occasionally appear depressed. During these conversations, the player can talk, either choosing to go along with the conversation or to tell Blathers to stop talking.
Blathers has the same role as he did in Wild World - accepting donations such as fish, insects, fossils and paintings, as well as identifying forgeries. He usually makes jokes and comments on fish and bugs, and will bluntly tell the player of his qualification in identifying fossils.
In Animal Crossing: City Folk, the root of Blathers' entomophobia (also known as insectophobia) is revealed: when he was younger, a mantis egg case ruptured on his writing desk, causing thousands of mantises to fly out. To hear this anecdote, a mantis must be donated to the museum.
In Animal Crossing: New Leaf, Blathers is in the museum again, having the same role as previous games. He can now identify multiple fossils at once, as well as accepting multiple donations at once. However, when the player donates to the museum, he does not talk ('blather') as much as in previous games. At some point in the game, Blathers requests a museum renovation as a public works project. When this is built, a second floor will be added to the museum, managed by Celeste. Also, after this renovation is made, Blathers will, at some point, request The Roost as a public works project. This building, unlike previous titles, is separate from the museum.
Blathers appears in the film alongside Celeste in the museum, where they meet Ai for the first time after Ai makes a loud scream after she has unexpectedly seen the fossils in the museum. When Ai speaks to Blathers, he typically begins a lecture on a dinosaur skeleton of a T-Rex, while Celeste is seen taking Ai away to The Roost to complete a delivery task set by Tom Nook.
 Other Appearances
 Super Smash Bros. Brawl
 Wild World
 Names in other languages