Conversation so far:
How does Act I of Finian's Rainbow open?
The local sheriff and Buzz Collins, front man for local senator Billboard Rawkins, demand the Rainbow Valley locals pay their taxes or else have their land auctioned off.
Who is the main character of Finian's Rainbow?
Finian McLonergan is the main character of Finian's Rainbow.
Are there any other main characters in Finian's Rainbow?
Another main character in Finian's Rainbow is Og

Question: What is his role?
Self-contained rewrite: What is Og's role in Finian's Rainbow?