Source : Webster's Revised Unabridged Dictionary (1913)

Merrymaker \Mer"ry*mak`er\, n.
   One who makes merriment or indulges in conviviality; a jovial
   comrade.

Source : WordNet®

merrymaker
     n : a celebrant who shares in a noisy party; "the clubs attract
         revelers as young as thirteen" [syn: {reveler}, {reveller}]