The proverbial phrase "big fish in a small pond" is used to describe an individual who holds a dominant position in a small, insignificant place or group. There are several synonyms for this phrase, including "top dog," "kingpin," "overlord," "bigwig," "big shot," and "small fry." Each of these terms captures the essence of being the most important and influential person in a particular setting. Other terms that could be used include "dominant figure," "leader," "boss," and "head honcho." Ultimately, all of these synonyms describe a person who wields a significant amount of power and influence over others in a smaller or less significant area or group.