Cartoon Characters "L"
Mr. LASSITER "You're speaking my language... fluent money"
Brief Character description: Villainous owner of KBST, rival station to KJEM.  Holds a grudge against Elzer Marcus for firing him early on in his career.
Appeared all-too-briefly in: KJEM
LAURA HOLLOWAY "Nobody understands me."
Brief Character description: 14 years old, her parents were tragically killed in an accident, and she is brought to Starlight house for a brief time.  She is extremely depressed and keeps to herself.  She is very talented at guitar and writes songs which she is reluctant to share with others due to her low self esteem. She appeared only in one episode.
Important or starring episodes: Alone Again.
LELA
Brief Character description: She is the oldest Starlight Girl.  In a flashback, she and Kimber are seen playing together as children.  She is also shown playing drums in Ashley & The Starlights.
Lela and other Characters: Like the other Starlight Girls, she does not know Jem is really Jerrica. 
LENA LERNER
Brief Character description: The First Lady of Soul (according to Jem)
Impersonating? Tina Turner
Appeared all-too-briefly in: The Jem Jam, Part 1 & 2.
LEON
Brief Character description: Electrician employed by Maison Fleur.
Appeared all-too-briefly in: Mardi Gras.
LEXA "Adriana dear!"
Brief Character description: Princess Adriana's cousin and pretender to the throne of Morvania.
Appeared all-too-briefly in: The Princess and the Singer
LILY LaROSE
Brief Character description: Bourbon Street chantuese (I assume fictional, she has lilac hair), who is the unrequited love of real-life pirate, Jean Lafitte.  Mlle. Yvette's great great grandmother; Shana strongly resembles her.
Appeared all-too-briefly in: Mardi Gras
LIN
Brief Character description: Chinese Jem fan, who is given Jem's earrings (long story) and returns them in time to save Jem's concert at the Great Wall.
Appeared all-too-briefly in: Adventure in China
LIN-Z (aka Lindsey Pierce)
Brief Character description: She is a v-jay, basically from MTV, she has her own rock and pop program.  Lin-Z is in the business, so she does have to promote the Misfits, but she is aligned mostly with Jem and the Holograms. 
Lin-Z and other Characters: Lin-Z knows a lot about the business and helped Jem and the Holograms a lot in the earlier years, introducing them to Anthony Julian and Video to name a few.
Important or starring episodes: Not really any.
Lindsey Pierce Model Sheet (Thanks Walter!)
LINC "Hey look, we're the Red Aces and we really don't like smart alecs"
Brief Character description: Illiterate "tough guy" and only named character from Roxy's old gang in Philadelphia.
Appeared all-too-briefly in: Roxy Rumbles.
LIZ STRATTON "Jem and the what?"
Brief Character description: Star and producer of a television miniseries, who hires Shana as her fashion designer.
Appeared all-too-briefly in: The Talent Search Part 1 & 2.
LUCKY
Brief Character description: Kimber's favourite horse, one of the few named animals on the show.
Appeared all-too-briefly in: Father's Day
LUIS GERALDO
Brief Character description: Jem's tour guide in Mexico.
Appeared all-too-briefly in: Aztec Enchantment
LUNA DARK 
Brief Character description: A person who is apparently pretty easy to pick up at the airport...
Impersonating?: Madonna.
Appeared all-too-briefly in: The Jem Jam, Part 1 & 2.