A When I started as a young secondary teacher, I remember feeling totally unprepared for dealing with older aggressive pupils in a school that had no policy or systems for managing behaviour and where every teacher was expected to cope on their own: to admit to having problems with a pupil or group was a sign of weakness and failure. Thankfully, most schools recognise the need for positive and collaborative cultures where staff, parents and pupils work together.
Your first step is to share your concerns with colleagues and be wary of going it alone. Consult your head of year or pastoral care head and check out whether other staff have had the same difficulties with this pupil, if there is any history of aggression, including what worked before to reduce it. In the unlikely event that this is out of the blue, keep a sense of perspective and try not to take this personally - you don't have to be liked by all pupils to be an effective teacher, and sometimes adults evoke strong emotions in youngsters through no fault of their own.
A decision could be made to involve a behaviour support team or educational psychologist for advice. Following classroom observations, some trigger points might be identified which appear to precipitate the pupil's hostility.
It is always worth asking what appears to lead up to unwanted behaviour patterns, what characterises interactions between staff and pupil, and what responses or consequences follow any given episode.
At some point a senior colleague will need to sit down with this pupil to discuss concerns openly. If the behaviour really is as threatening as you describe, then ask yourself why you would not want the parents or carers or other outside agencies to be aware of the situation - you may have someone dangerous in your midst. This is where a school's behaviour policy and discipline framework must be the point of reference for all concerned. This will provide an objective perspective on what is permitted and acceptable between pupils and staff.
Think clearly about the specific nature of this individual's negativity towards you and draw boundaries and guidelines, written down as a form of contract between the school and the pupil. This will include what strategies the pupil will use (for example, time-out, relaxation, visualisation), consequences of breaking the agreement, and how positive change will be recognised and celebrated.