Which is correct?

apostrophe "s" or no???

Sam wanting to rule the country sparks great controversy.

or

Sam's wanting to rule the country sparks great controversy.

Neither sentence is correct.

The second sentence is correct. The issue is the possessive noun form that's needed before the gerund:

http://grammar.ccc.commnet.edu/grammar/gerunds.htm#possessive

Thanks, Writeacher.

You're very welcome!

The correct option in this case is: "Sam's wanting to rule the country sparks great controversy."

Explanation:

When showing possession or ownership, we typically use an apostrophe followed by the letter "s" ('s). In this sentence, we are describing Sam's wanting to rule the country. "Sam's" indicates that the wanting belongs to Sam.

If we were to write "Sam wanting to rule the country sparks great controversy," it would imply that "wanting to rule the country" is a general statement and not specifically related to Sam. But since we are talking about Sam's desire to rule the country, we use the possessive form (Sam's) to indicate that the wanting belongs to him.

So, in this case, the apostrophe "s" is necessary to correctly convey the possessive form.