20 Celebrities You Forgot Guest Starred on Sister, Sister — Yep, That's Brittany Murphy!

Yep, Tahj Mowry — aka Tia and Tamera's real-life younger brother — guest starred on the show as three different characters, including Cousin Tahj in the season two episode "Get a Job," Sammy in the season three episode "Christmas," and T.J. in the season five episode "Child's Play."

Brittany Murphy played the recurring role of Sarah, Tia and Tamera's best friend, in the show's first season.

Gabrielle Union played the recurring role of Vanessa, Tia and Tamera's friend, during the end of the show's fourth season and the beginning of the fifth season.

We also spotted Taraji P. Henson playing Briana in a season five episode called "Two's Company."

Kobe Bryant played himself in "Kid-Napped," during which his character filmed a commercial with the father of a popular girl at Tia and Tamera's school named Rhonda.

Kenan Thompson and Kel Mitchell guest starred on the episode "Inherit the Twin," where they played Tia and Tamera's lawyers in student court.

Tia and Tamera went head-to-head with Mary-Kate and Ashley Olsen on a game show during the episode "Slime Party," and it went about as well as a slime party possibly could.

Keiko Agena, aka Lane Kim from Gilmore Girls, guest starred in the episode "Kid in Play" as an unnamed student.

Kyla Pratt — who you may recognise as Penny from The Proud Family — appeared in Tia's subconscious in the episode "The Road Less Travelled," during which Tia considers taking a summer internship with the WNBA.

Phill Lewis, aka Mr. Moseby from The Suite Life of Zack and Cody, can be spotted as Tia and Tamera's teacher Ed Berry, as well as a campaign consultant named Clifton McNair on two later episodes of the show.

Daphne Reid, who you might recognise as Aunt Viv from The Fresh Prince Of Bel-Air, also appeared on Sister Sister in the season four episode "Double Exposure," during which she played Charmagne, Ray's potential love interest. Fun fact: in real life, Reid is married to Tim Reid, who plays Tamera's father Ray Campbell on the show.

Scrubs star Donald Faison made an appearance in the season six episode "Greek to Me" as a the head of a fraternity that Tamera's boyfriend was investigating.

7th Heaven star Barry Watson made an appearance in season three as "Barney the surfer dude" in a two-part holiday special called "Thanksgiving in Hawaii."

That's So Raven's Orlando Brown was only 9 years old when he played Clayton, Tamera's blind date in the season four episode "Little Man Date."

Sherman Hemsley, known for his roles on The Jeffersons and The Fresh Prince of Bel-Air, played Tia and Tamera's grandpa Campbell in the season three episodes "Christmas" and "Shoeless."

Former professional basketball player Lisa Leslie also made an appearance on the show as herself in the season five episode "Ladies' Choice" and the season six episode "The Road Less Travelled."

Actress and "Dip It Low" singer Christina Milian guest starred on the show as Lana in the season four episode "Kid-Napped" and Girl Number 3 in season four's "When a Man Loves Two Women."

Rachael Harris guest starred on Sister Sister as Simone, a bossy college senior, in the season six episodes "Home Sweet Dorm," "Stop in the Name of Fun," "Home Court Advantage," "We Are Family," and "The Domino Effect."

RuPaul showed up in the season two episode "Put to the Test," during which the Drag Race host played a pretentious boutique owner named Marje.

Comedian and former Daily Show correspondent Larry Wilmore guest starred as a bus driver in the season one episode "Out Alone." Wilmore was also a story editor and writer for the show from 1994 to 1996.