The Demolitionist is a character that first appeared #284.
He is a dwarf who was the cause of Tyrone's fourth death (If counting the April's Fools special). He atomized him with a stick of Dynamite.
After Maxx gets back, he said that the crater the Demolitionist made will become his new house, as there isn't enough space.
His possible name could be Gimli which June said in comic #294
"I suppose even Aley wouldn't be much use here. I don't think fairy dust could de-atomize someone." -Hannah (#294)
- His name, Gimli, is a refrence to the Lord Of The Rings. Also, Gimli is one of the possible names of Demolitionist NPC in Terraria.