key figure

n. an important person in an event; a person central to an event. Sam is not exactly a key figure, but he can lead us to Mr. Big.

Name	Pronounced	Usage
Sonya	['səunjə]
Kader (1)	-	Arabic
Carmelita	[.ka:mə'li:tə]
Etheldreda	-	Medieval English
Princess	PRIN-ses, PRINT-səs, prin-SES	English (Modern)
Livvy	-	English