I dont think headliner. Other stage maybe

Sophie Williams (journalist and Mercury Prize judge) was on Huw Stephens' roundtable last week, said she'd love to see Overmono headline Green Man. Does feel like it's bound to happen. 2027 is surely on the cards seeing as they're about to release a new album 

Cat Power Wilco Whatever combination of Avalon Emerson and Aldous I manage to see Ken Pomeroy Sparks with an honourable mention to Neve Cariad

Saw em live back in march, and they were bloody marvellous - all flames, ghouls and skulls on sticks. And so tight musically! (i'm a Pleasure To Kill man in terms of albums, mind) 

Have ran out of upvotes.