The Ice King seems like one the most tragic characters I've ever seen. How he lost himself during the Mushroom war, protecting Marcy and trying to survive this apocaliptic world. Now he's alone and driven insain by the very thing (the crown) that's keeping him alive all this time. I hop, when they end the show, they give the Ice King some nice closure.
I like how his size compared with the height of the picture gives such a sense of isolation (or ice-olation...). Especially combined with all the blue and the cold, although that's natural anyway because that's where he lives, but it does really fit with his loneliness.