The boss. Him and his Irish mob ruled Boston for 3 decades. Everything illegal that went on in Massachusetts from Lowell to South Boston, whitey got a piece of it. Was seen as a Robin Hood figure to the oppressed Irish people of Boston. Born and raised in Southie. Kept Southie Irish, killed or ordered the killing of a couple dozen rival mobsters. Kept South Boston exclusively for the Irish, and helped out a lot of people in the neighborhood. When Whitey left and his empire collapsed most of his guys were either in prison, or hiding out in Irish parts of Massachusetts such as Lowell and Tewksbury.
Whitey Bulger had power of life and death over the Irish in Boston, he decided who lived and who died. They feared him, loved him, but ultimately relied on him and his guys to keep outsiders away from the Irish neighborhoods.