Richard Welstead Croker, known as "Boss Croker", was an Irish American political boss who was a leader of New York City's Tammany Hall. His control over the city was cemented with the 1897 election of Robert A. Van Wyck as the first mayor of all five boroughs. During his tenure as Grand Sachem, Boss Croker garnered a reputation for corruption and ruthlessness and was frequently the subject of investigations. As his power waned following the 1900 and 1901 elections, Croker resigned his position and returned to Ireland, where he spent the rest of his life.

In politics, a boss is a person who controls a faction or local branch of a political party. They do not necessarily hold public office themselves; most historical bosses did not, at least during the times of their greatest influence. Numerous officeholders in that unit are subordinate to the single boss in party affairs. Bosses may base their power on the support of numerous voters, usually organized voting blocs, and manage a coalition of these blocs and various other stakeholders. When the party wins, they typically control appointments in their unit, and have a voice at the higher levels. Reformers typically allege that political bosses are corrupt. This corruption is usually tied to patronage: the exchange of jobs, lucrative contracts and other political favors for votes, campaign contributions and sometimes outright bribes.