Old Man Watchitt is the mayor of Yold Town. Watchitt is known for saying "WATCH IT!", making fun of his name. In Yold Town, there is a gap in the town blocking Mario from continuing on in his adventure. This gap can be crossed by a bridge let down by Green. However, Green will only activate the bridge if Watchitt gives him premission. The hero must talk to Watchitt and ask if he can activate the bridge, but he will not call Green until you recieve Thoreau , a hand-shaped Pixl , also found in Yold Town. After the bridge is activated, Watchitt no longer plays a required role in the story.
Old Man Watchitt does play an optional role in the story. In the series of events that ends with the hero recieving Piccolo, Watchitt is the second-to-last character you need to talk to before you go back to the other characters you talked to on this errand. Bestovius will give Mario a Training Machine needed in this quest but will only do so if he recieves the You-Know-What from Watchitt. Watchitt will give you the You-Know-What only if you get an autograph from Merlumina.
Merlumina has been haunting Watchitt's dreams through-out the story, making Watchitt recieve little sleep (possibly explaining why he is always so angry). The haunting will only end when you get Merlumina's autograph in the errand. Watchitt is apparently related to Merlumina, as Merlumina could only haunt the dreams of a relative. This proves that Watchitt is also descended from the Tribe of Ancients.