Lavender Brown was a Gryffindor student in the same year as Harry Potter. She was best friends with Parvati Patil. Lavender tended to squeal and giggle a lot, and generally gave the impression of her being silly. She was keen on Divination, having been convinced of Trelawney’s powers after a vague prediction on the first day of class turned out (from one point of view) to have predicted the death of her pet rabbit, Binky (PA8).
In their fifth year, Lavender initially believed the Daily Prophet‘s insinuations about Harry, but Hermione shut her up (OP12).
Lavender attended the Yule Ball with Seamus Finnigan (GF22, OP11). Lavender was Ron’s girlfriend for few months in their sixth year; their relationship consisted mostly of making out. Ron wanted desperately to end it after awhile, but didn’t know how (HBP21, DH7).
Lavender’s saving grace was that she had the courage to be chosen for Gryffindor; during Hagrid’s disastrous experiment to determine whether Blast-Ended Skrewts hibernated (they do not), Lavender, far from fleeing with the Slytherins, stayed to help and got burned (GF22). Unlike Seamus, Lavender joined Dumbledore’s Army when it first formed (OP16), and she fought in the Battle of Hogwarts (DH31).
"lavender" = from Latin "lavare" to wash (because the plant lavender is used to perfume things by being washed with them).
In flower symbolism lavender symbolizes affection; cleansing; or concealment (something packed away can be said to be 'in lavender'). Lavender's herbal properties include the promotion of sleep and sound rest, another reason why sheets and linens were scented with it.
According to Donald Watts in the Dictionary of Plant Lore, traditional European plant lore held that lavender was a plant that flourishes when the woman, rather than the man, wears the pants in a relationship (223).
It is also the color associated with clothing made for elderly ladies.
Pureblood? Not in canon
In 2001 Rowling flashed a notebook during a BBC interview that showed her notes on the students in Harry Potter's year and Lavender is noted as being a Pureblood in Gryffindor House. Lavender's ancestry cannot be considered canon until Jo reconfirms it, however, because the notes conflict in too many places with the stories as they were actually published.
In the movies
In the movie "Harry Potter and the Prisoner of Azkaban," the role of Lavender Brown was played by Jennifer Smith. In "Harry Potter and the Half-Blood Prince" and both parts of the "Deathly Hallows" films, she was played by Jessie Cave. In the final battle scenes in the film, Lavender is seen lying on the ground being attacked by a werewolf. Some fans have mistakenly assumed that the character dies like in the film, but this isn't true. In the book Hermione intervenes before Fenrir Greyback even reached Lavender:
"Two bodies fell from the balcony overhead as they reached the ground, and a gray blur that Harry took for an animal sped four-legged across the hall to sink its teeth into one of the fallen.
'NO!' shrieked Hermione, and with a deafening blast from her wand, Fenrir Greyback was thrown backward from the feebly struggling body of Lavender Brown." (DH32)
The Girly Girl
Discussant Ed Kern on Episode 2 of the MuggleNet Academia Podcast noted that Lavender is a "stereotypically adolescent female." Many fans discussing the books in MuggleNet's Alohomora! Podcast took issue with the stereotype of "girly girls" like Lavender as being useless or just fluff characters. Many readers feel a connection with Lavender even if she is a bit extreme in her adoration of Won-Won. --Hufflepuffskein