The comedic plot of Shakespeare's tragicomedy The Merchant of Venice casts Antonio and Portia as the protagonists. Not much around Antonio is actually comedic, he is all in all a pretty serious guy. However Portia does gather together the elements of comedy at her villa estate on Belmont, presumably in the Adriatic Sea. An element of comedy are the scenes in which Portia and Nerissa exchange witticisms, particularly about Portia's suitors, and plot their intrigues. However the key figure in the comedic element of the play is Launcelot Gobbo.
Launcelot starts out as a lower class servant to Shylock and as such fills the Shakespearean role of Clown, a replacement for the Greek Chorus responsible for imparting additional information about principle characters, actions, and events. When Launcelot leaves Shylock's service and becomes the servant of Bassanio, who becomes the husband of Portia, Launcelot has a minor character shift and becomes a Shakespearean court Fool.
The difference between the Clown and the Fool is that the Clown is a lowly country dolt who usually doesn't know the wisdom of his own remarks, whereas a Fool is an urban fellow who chooses puns and character-directed witticisms intentionally. Scenes with Launcelot, e.g., with Old Gobbo, are key elements of the comedic plot.