A doctoral advisor (sometimes called a dissertation advisor) is a advanced member of a university faculty whose role is to guide a graduate student who is a candidate for a doctorate degree, helping them select coursework, as well as shaping, refining and directing the students' choice of sub-discipline in which they will be examined and/or on which they will write a dissertation. Students generally choose advisors based on their areas of interest within their discipline, their desire to work closely with particular graduate faculty, and the willingness and availability of those faculty to work with them.
Customarily, the student’s advisor serves as the chair of her or his doctoral examination and/or dissertation committee(s). In some cases, though, the person who serves those roles may be different from the faculty member who has most closely advised the student. For instance, in the Dutch academic system, only full professors (hoogleraren) may chair doctoral examinations, so students who have been advised by lower-ranked faculty members will have a full professor as their official promoter and their actual advisor as co-promoter.