In the U.S., that person would be known as a "PhD. Advisor". It is wise to choose one carefully so your research goals dovetail with their agenda. An unwise choice will almost certainly guarantee that you will not have the PhD. conferred. You must do original research for a PhD. and successfully defend your dissertation to a committee of faculty members. There are advisors in Master's degree programs, but their influence is limited mostly to structuring your program, and if you follow that plan, the university will confer the degree. If you complete the course work satisfactorily, you will almost certainly receive the degree. I have never heard of someone being denied a Master's, unless they willing abandoned and did not complete the requirements. I remember as an undergrad doing an individual investigation in chemistry, that one lab had a notice posted from an advisor to his graduate students which read, more or less: "Godd**n it guys, I expect more than five lab reports from you each week. If I have to write in a recommendation, that you do good work when you do any, but that I have to kick your a**es three times a day to get it, then you are DEAD as far as the job market is concerned." DEAD...that was his emphasis. Due to its inflammatory nature, the notice was only posted for a few days, but I managed to secure a copy of it. Ultimately, I decided to take an M.S. myself, chose a non-thesis option (more coursework) and was awarded the degree. Much less risk. But if you are looking for a tenured university faculty position, you will need that PhD. Competition for those jobs is keen. It might be wise to inform your plans with a thorough search for a job in the private sector, before embarking on a PhD.

That depends a lot on the country, and the university. Here, you must have at least one supervisor. Your supervisor(s) have responsibility for you, and in fact in most cases, you cannot do postgraduate study without finding a supervisor who is willing to supervise you, and who approves of your proposed study topic. Here, academic advisors are usually not members of faculty/academic staff, and they provide more general support, such as on how to write effectively, and on fulfilling other administrative requirements.

Thanks Gary and Tom!!! You helped me a lot!!!