By Ben Wright
Political correspondent, BBC News
Damian McBride resigned after making unfounded claims about senior Tories
Clare Short disparagingly dubbed them the "people who live in the dark".
On television The Thick of It portrayed them as scheming and mendacious Machiavellians.
One of the most infamous of recent years was Jo Moore. Now the name Damian McBride can be added to the list.
They can often be spotted darting through the television studios of Westminster with their minister, briefing papers under arm and Blackberry in hand.
Young, sharp and driven, they are the special advisers - and they get a bad rap.
The discovery that Mr McBride was smearing senior Conservatives in e-mails to his mate from his keyboard at Number 10 fits into that popular picture.
It has prompted Gordon Brown to ask the cabinet secretary to review the rules governing the behaviour of special advisers.
The Conservatives - and almost everyone who has read the rules - say that is unnecessary.
The code of conduct for special advisers is quite clear that they "should avoid anything which might reasonably lead to the criticism that people paid from public funds are being used for party political purposes". Damian McBride crashed through those rules.
So what do special advisers do and is the characterisation fair?
Jo Moore apologised for saying 9/11 was a day to "bury" bad news
The code of conduct spells out the job description. They are employed as temporary civil servants but do not have to be politically impartial like their civil service colleagues.
They link together the minister, the party and the department. They are also the bridge between the neutral civil service and the politicians.
One former "spad" - as they are known around Westminster - from the Blair years told me that they bring a political antenna to proceedings that essentially protects the civil servants by maintaining their independence.
They help write speeches, some are policy wonks, while others focus on the media.
Some journalists may sneer at the spads but they are an essential source of guidance and advice.
If a journalist wants to know what a cabinet minister thinks or understand what a policy is about, a call to the special adviser is one of the first ones to make. And very rarely is the person on the other end of the phone the ranting spinner of stereotype.
Special advisers first became a permanent fixture in Whitehall in the 1970s. But their number ballooned under Labour.
In 1996 there were 38 working in government costing the taxpayer £1.8m. In 2004 the number peaked at 84 and last year there were 73, at a cost of £5.9m.
But their expanded ranks prompted concern about their role. Critics felt a more American, politically driven civil service was sneaking in via the special advisers and a line of accountability was being blurred.
And the e-mail sent by special adviser Jo Moore after the terror attacks in the US on 11 September 2001 saying it would be a good "to bury" bad news triggered a number of reviews into their role and power.
A code was created and last year a draft civil service bill was published that would give Parliament the chance to nail down the exact function of such advisers. But that bill has long been promised and it's not clear when it will appear.
In the meantime, spads continue to roam the corridors of Whitehall.
Their close relationship to Cabinet ministers and lobby correspondents give them influence - an influence that can hatch into a political career later on.
A successful stint as a spad can be a crucial political apprenticeship - as many of the current crop of professional politicians including the Miliband brothers, David Cameron and George Osborne can testify - so long as they stay in the dark.