Was Mussolini the only person in Italy with power?

No, Mussolini was not the only person with power in Italy, although he was the dominant figure as the leader of the Fascist Party and the Prime Minister. His regime relied on a network of loyal supporters, including party officials, military leaders, and secret police, to maintain control. Additionally, the monarchy and various institutions still held some influence, though they ultimately supported Mussolini's authoritarian rule. Thus, while he was the central authority, power was shared among various entities within the state.