What constitutes a country legend?

Gunner classifies Merle Haggard as a country legend, and he was lucky enough to meet Merle prior to his death.

Is Garth Brooks a country legend? What about Reba? Or Alabama?

I would classify Willie Nelson, Dolly Parton and Kenny Rogers as country legends.

In order to be a country legend do you have to be deceased? Or over a certain age? Or have a certain number of hits?

Who do you classify as a country legend?