Goomba

Goomba appears in a movie, anime series and even on Sackboy's game. There's no contest.

I honestly have no idea of who or what Sackboy is or what he/she/it does.

I think it's safe to assume that a lot more people are aware of who Goomba is.

I honestly have no idea of who or what Goomba is or what he/she/it does.

I think it's safe to assume that a lot more people are aware of who Sackboy is. 

See two can play that games princess. 

It is safe to assume that a lot more people are aware of who Goomba is because of the sales of the games where he can be found. I never said that Sackboy's lesser popularity has anything to do with my awareness of him, and I'm certain that you know I didn't.

Don't be foolish.

How often is goomba actually reffered to in Mario games by name? Would people be able to pick out Goomba from name alone, I doubt it really. Maybe from a picture people would know its from a Mario game. Wheras with sackboy its immediately obvious what he is from his name, therfore should be more recognizable.   

That doesn't really matter. A character can be extremely popular without even having a name. There are other ways to recognize a character, after all.

Goombas appear, in one way or another, in almost every mario game ever (not just the main platformers).

Google Search results

Goomba-3,540,000
Sackboy- 2,810,000

Search results this year
Goomba- 199,000
Sackboy- 248,000