The term 'Vain One' can refer to three different people: an Egoist (6 letters), an EGOTIST (7 letters) and a FOP (3 letters). An Egoist is someone who is excessively concerned with their own interests and desires, often to the detriment of others. An EGOTIST is someone who is overly self-important and boastful, believing themselves to be superior to others. Finally, a FOP is someone who is overly concerned with their appearance and clothing, often in an attempt to impress others. All three terms refer to people who are overly concerned with themselves and their own interests.