In the language of British academia, a Fellow is a scholar who is financially supported by a college or university, for the purposes of research and/or teaching.
However, not all such people actually hold the title of "fellow", and it is difficult to establish precise rules for application of the title. In the newer universities, research fellowships are nearly always temporary posts, awarded to people who have completed doctoral and postdoctoral studies. (Persons of lesser seniority are usually called research assistants, and academics with permanent salaries are more often called lecturers.)
In the older British universities, the senior members of the individual colleges are called fellows. They are usually co-opted by the existing fellows, and often hold separate lecturerships in the university. Many of these fellows have pastoral responsibilities for the students of their own colleges.
