1. Head
The head is thought to be the most important part of the human body. So a leader is often compared to a head (首脑). Thus we have Head of State or the head of a delegation.
The head is where the brain is located. It is naturally associated with ideas and intelligence. Very often, we need other people's ideas and opinions when we want to do something well. The is because two heads are better than one (三个臭皮匠顶个诸葛亮).