(taken from tvtropes, a website where I could probably spend the rest of the week)

A character, usually female, is portrayed as helpless and in danger in order to put the cast in motion. In particular, the cast is unified, putting aside differences in pursuit of the rescue. This works especially well if the distressed damsel is a beloved character. Doesn’t work as well if the audience has grown annoyed by the character and doesn’t mind her dying (basically all of Lana Lang’s appearances as Victim Of The Week on Smallville). Easily becomes Narm if the character is someone who has been previously shown to be anything but helpless. Don’t expect her to do anything to aid her own escape either. Quite the contrary: the existence of a Damsel In Distress often precipitates a Dulcinea Effect. (And don’t expect anyone to give her any slack on this, even if the poor girl would logically *not* have the skills or abilities needed to help.) Some damsels do try to talk back or plan their escape, but this is still rare – and it doesn’t usually work.

Barbara Wright alternately played this trope straight and subverted it. The most memorable straight example would be in the very first Who serial An Unearthly Child, where she spends most of the last two episodes screaming and crying. She seems to have gotten it out of her system by the next serial, where she’s perfectly happy to go on a commando raid into the Dalek city. Her most memorable subversion is probably The Crusade, where she does get kidnapped, but rescues herself and is on her way back to rescue everyone else by the time Ian shows up to save her.

Although mentioned only briefly in the article, ourn Sarah! Jane! falls into this category and should have been given a ton more page space than the one line she got. Jo Grant was name checked (and so was Kathy (sic) Manning).

Ourn Liz? Not seen here, but found under a couple of other categories, namely The Hot Scientist and The Omnidisciplinary Scientist.

Click  here for an awesome and funny and spot-on comparison between ourn Sarah! Jane! and ourn Liz. Plus, Mrs. Gale vs Mrs. Peel! My money was on Mrs. Peel for years, but now I’m pretty much all for Mrs. Gale.

Thanks, Wes for the links to tvtropes and for reminding me it was there!