leader

is any member whose contributions are particularly indispensible. Insofar as any member is recognized by others as a dependable source of such contributions, he or she is leaderlike.

Newcomb, Turner and Convert (1965) observed that members of a group make different contributions to the achievement of goals. Insofar as any member's contributions are particularly indispensible, they may be regarded as leaderlike... and insofar as any member is recognized by others as a dependable source of such contributions, he or she is leaderlike.

NewcombThinkers

Newcomb