The Title Character
Typically when a character is mentioned in the title of a play or a book, the focus of the work is on them. However, this is ironic in this play since Figaro, the Barber, is not the main focus of the plot. That role falls to the Count. Although Figaro is instrumental to the success of the Count's plans, he is still secondary in terms of plot and actual spoken lines. He is the title character, yet not the main one.
Irony of Music Instructor
One of the many disguises Count Almaviva assumes to get closer to Rosine is that of an itinerant music instructor. This is a position of trust, because Rosine (like many young women of her class) is not allowed significant contact with men. Almaviva, whose intentions are honorable but romantic in nature, is choosing and deliberately subverting a position of trust. Meanwhile the real music teacher, who has been paid off by Almaviva, is actually a conniving person who is conspiring to force Rosine into an unwanted marriage with Dr. Bartholo.
Disguise Irony
Count Almaviva is afraid that the woman he marries will be interested in his wealth instead of loving him for his own sake. He therefore refrains from courting any of the women from families he knows, and decides that he is in love with Rosine, a young woman he has never actually met or spoken to, whom he has seen only once. Stalker-like, he follows her from Madrid to Seville. He assumes not one but two different disguises to insinuate his way into her guardian's household to pursue a budding relationship with her. Then, he is astonished when word of his interest in Rosine spreads around town and when his actions are interpreted as dishonesty and as part of a plan to abduct Rosine.
Irony of Dishonesty
Figaro, who is a pivotal character in the play but not the protagonist, is a very skilled liar and manipulator. So, for that matter, is Count Almaviva. These characters are willing to do some very dishonest things in order to get what they want. Almaviva lies, bribes, and conducts himself in an extremely dishonest manner but ironically he's the protagonist. Under normal circumstances the protagonist is supposed to be a virtuous hero of some kind.
Irony of the Judge
The judge Bartholo fetches to write up the marriage contract between himself and Rosine ironically writes up a contract for a marriage between Rosine and Count Almaviva instead. This is the exact opposite of what Bartholo intended.
Dramatic Irony
The audience is fully aware that Lindor, the drunken soldier, and the music teacher are all disguises of Almaviva's. Rosine, however, is unaware of "Lindor's" true identity and accordingly believes Bartholo when he informs her about Count Almaviva's supposed kidnapping plot.
