The title of the person in charge of the opposition is the leader of the opposition. This is the term that is used in most countries. The opposition serves as a watchdog to the government.
The title of the person appointed by the court to settle the estate of a person who left a will is the executor.
Police comissioner
Icelander
Rural
a soundtrack person or the person who is in charge of the music department for that film
The Queen or someone on behalf of her.
I believe this is the Quartermaster.
CFO or Chief Financial Officer
The CEO, President or person with a similar title is the head of a modeling agency.
Thomas Mulcair (NDP)
Opposition is whatever is challenging you.
John McCain.