He is a fast/slow 'walker'. [=he walks at a fast/slow pace]
She joined a group of 'walkers' in the neighborhood.
(..) - Man: Accept?! We need this dragonglass, my lords! We know that dragonglass can destroy both white walkers and their army. We need to mine it and turn it into weapons. But more importantly, we need allies! (..)2017 TvShow: Game of Thrones Title: Stormborn Season: 7 Episode 2