A person who behaves obsequiously in order to gain advantage.
Derivation: Mid 16th century (denoting an informer): from French sycophante, or via Latin from Greek sukophantēs 'informer', from sukon 'fig' + phainein 'to show', perhaps with reference to making the insulting gesture of the ‘fig’ (sticking the thumb between two fingers) to informers.
There's a trend I see in every part of life where groups are organised: It's the growth of a system of patronage and the fawning that goes with it. Destructive obsequiousness is lurking in every moment and every place. Here's one example: A while back the West Australian published in its Inside Cover section the story of a missing EPIRB from an Australian naval vessel. It had fallen from a ship's boat and provoked a major search in the waters off Perth. Although the search was high-profile, the revelation that it was all a false alarm due to some negligence by a naval rating was suppressed until a civilian who'd heard about it on marine radio asked Inside Cover why the outcome hadn't been published. IS published the "secret" without revealing the source. This provoked a witch-hunt in the Navy and Defence Department as various catchfarts tried frantically to appease their bosses by finding what they believed was a leaker. More and more time and effort was wasted until a real whistleblower called IS and begged them to take the heat off. IS published the obvious fact that the operation and its outcome had been broadcast on open frequency at the time and no leaking was necessary. They also asked why, if the public was allowed to know of the search, they weren't allowed to know the true cause. This is indicative of a typical quality of the crawler: stupidity.
It's not as though power hasn't done everything it can to discourage those who want to tell it the truth. The story of the sailor hanged for warning the Admiral of impending doom may be apocryphal, but the pattern is present in history. Not for nothing was the phrase "killing the messenger" added to the list of classic cliches. In the Soviet Union of blessed memory the intelligence agencies were obliged to provide Brezhnev with reports which conformed to his expectation of Western conspiracies. Failing to do so would have been seen as suspect. The realistic assessor would risk condemnation as an appeaser or traitor.
Here's a couple of anecdotes from my own observation and experience:
Once, in an organisation where I was conducting an audit, I discovered a serious misprint in a contract form which, through a simple transposition of words nullified the effect of the document as a protection of the organisation's interests. I was finally able to convince the person in charge of publications of the obvious, but met a final obstacle. Although convinced of the error, this character wouldn't alter the printing template, insisting that an instruction had to come from the responsible area. I responded by asking whether the proper authorisation to make a cock-up had been received. When I was finally able to nail that point home I asked the simple question: If you made the mistake without permission, why do you need permission to fix it? To no avail; the habit of refraining from use of common sense or guts was too deeply ingrained. I gave up in disgust and left the fools to their devices. I didn't have the energy to pursue it with some mug who would have simply referred the matter endlessly upwards until the CEO referred me back to publications. Another characteristic of the crawler: they prevent the correction of mistakes.
A person of my acqaintance who had been employed as an administrative assistant in a local government district was instructed by the supervisor in the manners of the office. One of the rules was to not make eye contact with the councillors if they happened to be wandering the building and walked past. This was to avoid the disrepect involved in engaging them in acknowledging the staff with a nod or a "G'day". The crawler creates neurosis and paranoia.
In a Federal law enforcement agency, I once had to organise the taking of minutes of a meeting where some senior managers were in attendance. A major obstacle arose when the minute-takers couldn't figure how many "r's" were in one man's surname. I resolved the protracted argument by approaching the guy and asking him. This was considered highly unconventional and bold and added to my mana as a lateral thinker. This sort of reckless use of common sense led to my horrifying another gang of fleas by asking a senior manager at another meeting for his name for the minutes. On this occasion I was visiting another city and the fleas nearly fell off their chairs at my temerity. I asked them why they would expect a person from out of town to guess the name of a complete stranger. Utter bafflement. Apparently some enormously obscure operation carried out by subterfuge was the proper practice to find out such things. The crawler wastes everybody else's time and effort.
The crawler prospers because those who should know better and should resist the corrosion of their domain by fawners encourage them. The love of obedience and deference by the "leaders" is at least as much to blame as the inclinations to servility by their followers. The essence of it is that the sycophant is no-one's friend. Their sole focus is on their own interest. That's hard for the powerful to remember, but it's vital; the person who relentlessly agrees is not loyal to you or your cause. They're willing to let you run on the rocks rather than risk the cost of correcting your course.