Farfarello was a Malebranche. Malebranche is the name of the legion of demons that guards the corrupt ditch. Malebranche means "Evil Claws".

Farfarello appears in two parts, called "Cantos", of the book: the XXIst, and and the XXIInd. Each demon's names have a significance. The exact translation of "Farfarello", is "Elf", or, in a more free translation, "Leprechaun", an Irish folklore figure. It has also been translated as "evil ghost."

Passages:

CANTO XXI

(...)And so, Malacoda designated ten devils to escort us, calling each one of them by their names: Calcabrina, Alichino, Cagnazzo, Libicocco, Draghignazzo, Graffiacane, Ciriatto, Farfarello, Rubicante and Barbariccia, the leader of the expedition.
- My master, what am I seeing? - I said, scared - refuse the escort and let us go by ourselves, for I don't what their company. If you pay attention, like you always do, see how they show there teeth and blink at each other.
- There is nothing to fear - the master answered - let them show their teeth at will. They are doing it at the souls that burn, not to us.
Before we continued by the left edge, the demons saluted Malacoda, blowing, with the tongue between their teeth, making an obscene sound.(...)

CANTO XXII

We followed the ten demons. (...) [Sinners] remained at the cesspool border, but they would submerge as soon as Barbariccia would appear.
I've seen a hesitant sinner that took some more time to return to the burning pond. Before the poor man could submerge, Graffiacane grabbed him by his hair. The devils screamed:
- Oh Rubicante! Stick your claws in his back! Tear the skin!!
(...)
Ciriatto, that had two fangs like the ones of a boar, showed him how only one of them could tear him apart. But Barbariccia interfered, grabbing him.
- Take your chance while I'm holding him! - Barbariccia told Virgilio - If you want the sinner to speak more, interrogate him before the others dilacerate him.
(...)
- We waited to long! - Libicocco screamed, ripping a peace of the sinner's arm with his fork. Draghinazzo was also going at it, but gave up when he understood the decurion Barbariccia was staring at him with an irritated look.
(...) Barbaraccia turned to Farfarello, that got nearer, and screamed:
- Retreat, you disgusting bird of prey.(...)

[reading the all canto is advised]

[more about Dante's Inferno and Farfarello]