Like other once-powerful houses, House Baratheon is all but out of the picture. All its legal heirs are dead (and some of those heirs, such as Joffrey and Tommen, weren't even biologically Baratheons). So why do they still matter?
One word: Gendry. The young blacksmith who befriended Arya Stark long ago is the last known descendant of Robert Baratheon, although he's illegitimate. After disappearing for quite some time, Gendry escapes from Lannister territory and joins the Targaryen/Stark cause, bonding with Jon Snow in a parallel to their (supposed) fathers' friendship. Gendry joins the fight against the wights and is last seen returning safely from battle and sending a plea for backup to Daenerys.