Written OOC-ly with a bit of assistance from Sarah Jane. I'm also debating adding entries pertaining to her time with the Doctor and UNIT.
EDIT(04/26/2011): I am adding entries and information for people and places from the older series, as well as those introduced in the latest season of the Sarah Jane Adventures. It will take a while, but I'll get it done.
A
The Abomination -
“The Attic” - Sarah Jane's Attic, to be precise. This is basically her command center. Mr. Smith and K-9 reside here, as does Sarah Jane's collection of alien artifacts, UNIT files, and other extraterrestrial miscellanea. Often times, when Rani and/or Clyde visit, they hang out here. (The Attic door is where Sarah Jane enters the Loft.)
The Ancient Lights -
B
The Bane - An extraterrestrial plant-based life-form. They are sentient and exhibit characteristic of animals as well as plants. Bane society consists of “families” let by Bane Mothers, though it is unknown if the members of this family are unrelated. Even with this kind of structuring, however, the Bane are cannibalistic, with the punishment for failure, disobedience, and crimes being something along the lines of being eaten by the perpetrator's Mother. The Bane can mimic human form, and are destroyed with sound waves of a certain frequency.
Blathereen -
C
Gita Chandra - Rani's mother. She's a very kind and warm person, but a bit talkative. She runs a florist in town by the name of Bloomin' Lovely. She really does like plants. One thing, though: She calls Sarah Jane “Sarah”. She doesn't like that (The Doctor, Harry, and the Brigadier are exceptions).
Haresh Chandra - Rani's father, and Head Teacher at Park Vale School. Being so, he's got a strong sense of formality and order, and is very perceptive. Though he is tough, he's very caring of both Gita and Rani. However, he's not so keen on Clyde.
Rani Chandra - Another friend of Luke and Sarah Jane, as well as Clyde. She moved in over the road with her parents shortly after Alan and Maria left. She's inquisitive and quick-thinking, like Sarah Jane. She even wants to be an investigative journalist when she's older. Also, she's one to Clyde talk down of an ego trip, but not in a mean way. Daughter of Gita and Haresh Chandra.
D
The Doctor - A very human-like extraterrestrial who travels in time and space. Has had many different faces due to a process known as “Regeneration” that occurs if he is fatally injured. He is quite unpredictable and very clever. Has a fascination with Earth and the inhabiting humans, but quite disfavors them at times.
E
Eldrad -
F
G
Gorgon -
Grask -
Grosk -
H
I
J
Alan Jackson - Maria's father, and an overall nice guy. He's brilliant with computers, and really cares about Maria. He even helped Sarah Jane and the others a lot. Moved to America after he was offered a job in Washington D.C.
Chrissy Jackson - Maria's mother. She's separated from Alan, and has a boyfriend named Ivan. She acted a bit empty-headed, but wasn't really. She cares about Maria and can read Alan like a book. She even took down a Sontaran! If only she could get Sarah Jane's name right...
Maria Jackson - 13-year-old girl who lived over the road from Sarah Jane with her dad. She helped with alien investigations and such. Recently moved to America with her dad, but keeps in touch whenever she can. Daughter of Alan and Chrissy Jackson.
K
K-9 Mark III - A dog-shaped computer, complete with little satellite ears and a waggly tail. Despite the cuteness, though, 'he' is quite an advanced piece of equipment. He's a supercomputer that's equipped with a small scale, multi-setting laser beam, voice recognition, and self-mobility. Quite the personality, as well. Was destroyed in a blast that saved the universe against bat-like aliens and quickly replaced with an upgraded model. Was a gift from the Doctor, picked up in 1981, three years after it was initially sent.
K-9 Mark IV - An improved version of K-9 Mark III. This model retains all of the previous one's functions, as well as an artificial sense of smell, low levitation capabilities, and his own dog whistle. Received in 2008 as a gift from the Doctor, along with the Sonic Lipstick and Scanner Watch.
L
Alistair Gordon Lethbridge-Stewart - Formally a Brigadier in service of UNIT and a good friend of Sarah Jane's. Although he is retired, he is called on for special assignments. He is overall bitter about how UNIT handles things nowadays, but still works hard at what he does. He helped Sarah Jane and Rani break into the Black Archive, a repository of alien artifacts, to get hold of an artifact for a Bane criminal.
Carla Langer - Clyde's mother. She's straight-up, smart, and generally a nice person. She's currently teaching Clyde to cook.
Clyde Langer - A friend of Luke and Sarah Jane. He lives with his mom a couple of houses down from Sarah Jane. He's a very practical thinker, and likes to maintain a “cool” image. He's a good artist, laid back, and likes K-9.
M
Mona Lisa -
N
O
P
Park Vale School - Educational institute in Ealing that Luke, Clyde, and Rani attend. Many of the supernatural happenings that Sarah Jane and the others face occur or spread here.
Q
R
Racweed - A plant originating from Raxacoricofallapatorius. Though it is labeled as a food source, Racweed is highly addictive. In its dormant state, it is stationary and harmless, but when exposed to sunlight, it blooms, releasing spores. The spores are quick to adapt and grow in any host material, even human skin. If a human is infected, however, it is not directly fatal. The spores will, however, drain the host of their energy, resulting in an irreversible coma. Individual blooms will emit a sort of screeching noise, which it uses to communicate with other mature Racweed. This is essential to the plant's life cycle, but is able to be overridden and broken by another sound wave of a specific frequency.
S
Scanner Watch - A normal watch, it seems, until you flip open the top. It's really an alien scanner! Most often used to detect an extraterrestrial visitor's vitals, it has recently been shown to detect and trace the presence of such visitors. Also, the watch part really works, which helps convince the neighbors. Received as a gift from the Doctor, along with the Sonic Lipstick and K-9 Mark IV.
Slitheen - A family(rather than a race) of extraterrestrials from the planet of Raxacoricofallapatorius. Physically, they are green with long necks, arms, and claws, large eyes and faces that are wider then they are taller. The entire Slitheen family, or quite a lot of them, are criminals and don't think much of devastating the Earth in order to make a quick buck. Their race is calcium-based, which makes vinegar fatal to them. They can mimic human form, but their compression technology has one drawback: gas exchange. Once inter-married with the Blathereen, another family of their race.
Mr. Smith - A supercomputer with a Xylok consciousness as the central processor. Crashed on Earth in prehistoric times, and was trapped beneath the ground until a volcanic eruption eons later brought 'him' to the surface. Sarah Jane's personal resource-finder, though 'he' also assists Luke and Clyde with school projects.
Barbara Smith -
Eddie Smith -
Lavinia Smith - Sarah Jane's aunt on her father's side, and her legal guardian for most of her younger life. She was a scientist famous within the UK, which is how Sarah Jane got herself into the situation where she met the Doctor for the first time. Lavinia also raised Brendan Richards, who was just a little younger than Sarah Jane. She had held on to the package that contained K-9 Mark III from 1978 to 1981 before leaving it at her new house for Sarah Jane to find on a visit. Sarah Jane actually picked up a good few of her prominent character traits from Lavinia.
Luke Smith - Originally created as a human archetype by the Bane for research. Once the Bane were bested by Sarah Jane Smith and Maria Jackson, Sarah Jane adopted him and named him Luke. Mr. Smith forged all the papers.
Sonic Lipstick - A device similar to the Sonic Screwdriver. It serves as a multi-tool, able to unlock doors, take apart and perform maintenance on small devices, or generally break larger ones using condensed sound waves. A present from the Doctor, received in 2008 along with K-9 Mark IV and the Scanner Watch.
Sontaran - A race of genetic clones from the planet Sontar. They are very militaristic, living only to fight, and hold honor above all else. They look like anthropomorphic potatoes, but their minds are packed with more intergalactic battle tactics than all the war rooms on most planets. Also, they are nearly indestructible. Any method of killing them involves the probic vent on the back of their suits, where their neck should be.
Harry Sullivan -
Sutekh -
T
TARDIS - The Doctor's preferred mode of transportation. On the outside, it appears to be a 1960's era police box right off of the streets of London. The inside, however, is its own pocket dimension. It's very large, and very non-police-box-like. It even has multiple rooms for lodging and things. The Doctor is connected to it through Time Lord technology, and must retire to it once he's regenerated.
The Trickster - A being from beyond time and space, and an embodiment of chaos. In the beginning, he attempted to take Sarah Jane out of her time stream and use her to get closer to the Doctor. Is that all the older companions are for nowadays? Anyways, after he was defeated, he swore his revenge on Sarah Jane. Twice, so far, he's attempted revenge, but failed both times. There is no currently documented way to destroy him.
U
UNIT - United Intelligence Taskforce. The official authority on extraterrestrial beings. While, in recent years, they have been moving more into a scientific approach, UNIT remains mostly militaristic in nature, causing disfavor in the eyes of those like Sarah Jane and the Doctor. Clyde aspires to be part of UNIT one day.
V
W
Warp Star -
X
Xylok - An extraterrestrial crystalline life-form. It has the ability to communicate through electronic devices. Mr. Smith is one.
Y
Mike Yates -
Z