Birth name: Fred and George Weasley.
Birthdate: April 1, 1978.
Name meaning: Weasley="In Britain and Ireland the weasel has a bad reputation as an unfortunate, even malevolent, animal. However, since childhood I have had a great fondness for the Family Mustelidae; not so much malignant as maligned, in my opinion." This genus includes weasels, stoats, polecats, ferrets, mink, wolverines, badgers, skunks, otters, and others.

Ancestry: Pure-blood.
Mother: Molly (Prewett) Weasley.
Father: Arthur Weasley, Head of Misuse of Muggle Artifacts Office, Ministry of Magic.
Maternal grandparents: Molly and Sirius are "cousins by marriage," so Molly's parents are probably related in some way to the Prewetts listed on the Black Family Tree.
Paternal grandparents: Septimus and Cedrella Weasley.
Siblings: Bill, Charlie, Percy, Ron and Ginny.
Location of childhood home: "The Burrow," near Ottery St. Catchpole, Devon (second floor bedroom); currently living in a flat above their shop at 93 Diagon Alley.
Creatures associated: The family owl (Errol), family ghoul, Nifflers (OP31), garden gnome disguised as Christmas tree angel (HBP16).

Eyes: unknown.
Hair color: Flaming red.
Other characteristics: Freckles. Body type similar to their shorter, stockier brother Charlie (GF5). For Christmas their third year, Molly gave them blue "Weasley" sweaters, one with a large yellow F on it, the other a G.

First year: 1989.
House: Gryffindor.
Quidditch: Beaters for Gryffindor, they use Cleansweep Five broomsticks. Banned for life by Dolores Umbridge after post-game brawling with Draco Malfoy.
OWLs: They both got 3 OWLs -- Ron got 7.
Fred's Yule Ball date: Angelina Johnson.
Awards, prizes, etc.: Fred and George have a whole drawer in Filch's "punishment" cabinet all to themselves. Professor Flitwick was so taken with the Portable Swamp that the twins created on a school corridor that he left a small part of it in their honor.
Finished school? No, the twins quit school before the end of their 7th year in a final act of defiance against Headmaster Dolores Umbridge.

Wands: Unknown.
Skills: the twins are unusually adept at charms as their many inventions show; they also have a flair for business and a knack for finding secret passages at Hogwarts.
Quidditch World Cup: During the Quidditch World Cup, they placed a bet with Ludo Bagman for all of their money (thirty-seven Galleons, fifteen Sickles, three Knuts) that Ireland would win, "but Viktor Krum gets the Snitch." They won, but unfortunately Bagman cheated them by giving them Leprechaun gold that vanished the next morning.
Spells & potions: Aging potion, jelly legs, Garrotting Gas.
Organizations & affiliations: The twins were some of the first wizards to meet Harry, and they have always been unhesitatingly loyal (in their own way). They helped Harry deal with being ostracized over being a Parseltongue by preceding him through the hallways shouting "Make way for the Heir of Slytherin, seriously evil wizard coming through." They were also members of Dumbledore's Army.