This page fills in the details of the cast, with various snippets about what they've been up to over 8 years. The information is by no means exhaustive - The information given is for the characters in 90210 and not the actors who play them just in case there is any confusion :)

Brandon Walsh
Played by Jason Priestley - born 28th August 1969 in Vancouver, British Colombia, Canada.
Lost virginity to : Sheryl, a past love from Minnesota, in Brandon's room at Casa Walsh (in 1.04 : The First Time).
Engaged to : Kelly Taylor (8.29 : Ricochet).
Parents : Jim & Cindy Walsh.
Appeared in : All seasons to date.

Character Low Points : Crashes his car after drink driving (1.11 - afterwards checks into Alcoholics Anonymous); almost killed after slipping off a cliff edge (2.07); unknowingly takes Euphoria drug (2.15); gambling problem (3.18, 3.19, 3.20, 3.21, 3.23); almost involved in a plane crash (4.15); friend Josh Richland is killed in a car crash (5.03, 5.04); gets stuck in an elevator with Susan, and helps deliver a baby (6.09); gambling problem resurfaces (6.14); drinking (7.32).

Brenda Walsh
Played by Shannen Doherty - born 12th April 1971 in Memphis, Tennessee, U.S.A.
Lost virginity to : Dylan McKay, in a hotel room during the Spring Dance (in 1.21 : Spring Dance).
Parents : Jim & Cindy Walsh.
Appeared in : Seasons 1, 2, 3, and 4.

Character Low Points : Car accident (2.20); goes to Mexico with Dylan without permission, and gets caught (2.27, 2.28); smoking cigarettes (3.04, 3.05, 3.08); Involved in the Kelly/Brenda/Dylan love triangle (latter Season 3); almost involved in a plane crash (4.15); gets arrested and thrown in jail after attempting to raid an animal testing lab (4.23, 4.24).

Kelly Taylor
Played by Jennie Garth - born 3rd April 1972 in Urbana-Champaign, Illnois, U.S.A
Lost virginity to : Ross Webber (mentioned in 1.13 : Slumber Party at Brenda's girls-only night); seen in 8.27 : Reunion.
Parents : Bill & Jackie Taylor (divorced).
Engaged to : Brandon Walsh (8.29 : Ricochet).
Appeared in : All seasons to date.

Character Low Points : Involved in the Kelly/Brenda/Dylan love triangle (latter Season 3); Abuses diet pills (3.23, 3.24); becomes stuck in the basement at Steve's rave when the fire occurs (5.13); becomes involved in Professor Finley's cult (5.17, 5.18, 5.19, 5.20, 5.21); gets hooked on cocaine (6.17, 6.18, 6.19, 6.20, 6.21); has a miscarriage and learns she may never be able to have children (7.30).

Steve Sanders
Played by Ian Ziering - born 30th March 1964 in West Orange, New Jersey, U.S.A.
Lost virginity to : Kelly Taylor, at The Beach Club [before episode 1.01] (mentioned in 7.02 : Here We Go Again).
Parents : Karen Brown (deceased), Rush Sanders; Adoptive mother - Samantha Sanders (once married to Rush, but now divorced).
Appeared in : All seasons to date.

Character Low Points : Steals history tests (1.06); searches for his roots, and locates his grandfather, only to find that his real mother was killed in a car accident (2.18); takes steroids (2.20); trys to hack into the school computers to change his grades (3.12, continued in 3.13, 3.14) and is expelled from High School (3.14); a fire at his and Griffin's rave (5.13) lands him in court and 100 hours of community service (5.14); steals Brandon's term paper, claims it as his own (7.10) and gets expelled from college (7.11); smokes pot (7.19).

Andrea Zuckerman (-Vasques)
Played by Gabrielle Carteris - born 1st February 1961 in Phoenix, Arizona, U.S.A.
Lost virginity to : Dan Rubin in her college dormitory (in 4.06 : Strangers in the Night).
Now married to : Jesse Vasques (although now facing divorce).
Parents : Kenneth & Gail Zuckerman
Appeared in : Seasons 1, 2, 3, 4, and 5 until 5.30 (also 6.31, 6.32 and 8.27).

Character Low Points : Goes to West Beverly High School, despite living out of district (1.01, [mentioned in 1.05, 1.07], and is found out (2.12)); gets hit by a car and breaks both legs (3.12); announces that she is divorcing Jesse (8.27).

Dylan McKay
Played by Luke Perry - born 11th October 1966 in Mansfield, Ohio, U.S.A.
Lost virginity to : Unknown.
Parents : Jack & Iris McKay (divorced).
Appeared in : Seasons 1, 2, 3, 4, 5, 6 until 6.10.

Character Low Points : Surfing accident (2.03); drink problem (2.08, 2.10, checks into Alcoholics Anonymous afterwards); drops out of school after being wrongly accused of cheating in an SAT test (3.13); father, Jack Mckay dies in a car bomb explosion (3.21); Involved in the Kelly/Brenda/Dylan love triangle (latter Season 3); drink problem again (5.01, 5.02, 5.03, 5.04, 5.05, 5.06, 5.07); crashes his car after taking coke, heroin, and drinking (5.08, 5.09); wife, Toni Marchette killed by gunmen (6.10).

David Silver
Played by Brian Austin Green - born 15th July 1973 in Van Nuys, California, U.S.A.
Lost virginity to : Ariel Hunter (mentioned in 4.31 : Mr. Walsh Goes To Washington [Part 1]).
Parents : Mel & Sheila Silver (divorced).
Appeared in : All seasons to date.

Character Low Points : Drives Steve's car without a licence, and crashes (1.01); best friend Scott Scanlon dies from a fatal, self-inflicted gunshot (2.14); gets serious feedback whilst performing in a music showcase (3.14); gets hooked on speed and crack (4.16, continued in 4.17, 4.18, 4.19, 4.20); grandfather dies of a heart attack (7.07); gets hooked on gambling (7.10).

Donna Martin
Played by Tori Spelling - born 16th May 1973 in Los Angeles, California, U.S.A.
Lost virginity to : David Silver, at the Beach Appartment (in 7.32 : Graduation Day [Part 2]).
Parents : John & Felice Martin.
Appeared in : All seasons to date.

Character Low Points : Gets a low SAT score, and finds out about her learning disability (1.19); Caught drinking at the High School Prom and expelled from West Beverly (3.27, continued in 3.28); almost raped by Garret Slan at the beach appartment (5.23); pushed down stairs by Ray (5.31); held at gunpoint by Evan at the California University T.V. station (7.18); walks out of her final college exam after a memory blockage (7.30); grandmother dies of a heart attack (8.19); starts taking drugs (8.21, 8.22, 8.23).

Valerie Malone
Played by Tiffani-Amber Thiessen - born 23rd January 1974 in Long Beach, California, U.S.A
Lost virginity to : Tom Miller, in Buffalo [before episode 1.01] (mentioned in 7.14 : Jobbed).
Parents : Abby Malone, deceased father Victor Malone.
Appeared in : Seasons 5 to the present.

Character Low Points : Smokes pot (5.01, 5.05); Derrick Driscoll steals $100,000 (7.30); attempts to commit suicide (7.32).

Claire Arnold
Played by Kathleen Robertson - born 8th July 1973 in Hamilton, Ontario, Canada
Lost virginity to : Unknown
Parents : Chancellor A. Arnold, deceased mother.
Appeared in : Seasons 4, 5, 6 and 7.

Character Low Points : Finds out about Steve and Kelly's past relationship (7.01); father moves to Paris, and is forced to move too (7.30, 7.31, 7.32).