Which pope is strongly linked to the Investiture Controversy in the late 11th century?

The story behind the answer

As the reforming pontiff of 1073–1085, he ignited the Investiture Controversy by banning lay investiture—secular rulers appointing bishops—and asserting sweeping papal authority in the Dictatus Papae. His fierce clash with Emperor Henry IV led to multiple excommunications and the dramatic Walk to Canossa in 1077, where the emperor sought absolution, symbolizing papal power over kings.

This struggle was central to the broader Gregorian Reform, which targeted simony and enforced clerical celibacy to purify church leadership. Though the dispute wasn’t fully resolved until the Concordat of Worms in 1122, it reshaped medieval Europe by delineating the boundaries between spiritual and temporal authority and set a precedent for later conflicts between church and state.