Tutivillus

Meaning:  Depending on the era/writer, Tutivillus is the devil responsible for collecting the words of gossips, to be reported against them in heaven, or the errors priests made in liturgy*, ditto. He is also referred to as the "patron demon of scribes", causing errors such as haplography. As is appropriate, his name has any number of possible spellings, including Titivullis. There's more about him here, here or here.

Usefulness: 1 (However scanty the evidence for his past existence may be, we need a typo demon.)

Logofascination: 1 (After various roles in the Mystery Plays, he evolved into a word, titivil, and allegedly shows up twice in Shakespeare as tilly-vally or tilly-fally. That's quite a career, particularly when you consider what small errors it is built on - Screwtape would be impressed.)

In the wild: Yes, although you have to take into account the eight different spellings.

Degrees: 2 (by word; the example below is one of the early Tutivillus stories with the name removed.)

Connections: Tutivillus - devil

Which is used in: G&P, Book the First (Gargantua), VI: How Gargantua was born in a strange manner.  The midwives attending Gargantua's mother have given her medicines which have made her terribly constipated, and Rabelais discusses this as only Rabelais would:

whereby all her larris, arse-pipes, and conduits were so oppilated, stopped, obstructed, and contracted, that you could hardly have opened and enlarged them with your teeth, which is a terrible thing to think upon; seeing the Devil at the mass at Saint Martin's was puzzled with the like task, when with his teeth he had lengthened out the parchment whereon he wrote the tittle-tattle of two young mangy whores.

In order to stop you thinking too much about that first image, I'll point out that Rabelais' story of a devil having to lengthen his parchment because there was so much gossip to record is generally associated with Tutivillus. Also that the 'mangy whore' seems to have come from Sir Thomas in translation - Rabelais has gualoises, which should possibly be gauloises. Sir Thomas sometimes picked up such things from Cotgrave, but Cotgrave only has 

Gaulois: m. ise: f. Of France, French, a Frenchman.

Perhaps Sir Thomas had a poor opinion of Frenchwomen.

*Latin is quite tricky.