Edward Brooke-Hitching, The Madman's Library: The Strangest Books, Manuscripts and Other Literary Curiosities From History
(London: Simon & Schuster, 2020) p. 173:
So vexing was the possibility of error for even the most accomplished scribe that we ﬁnd references and illustrations of it personiﬁed in demon form. Titivillus, known as 'the patron demon of scribes', was said to be sent by Lucifer to torment the tired scribe and trick him into bringing errors into his work, and is ﬁrst referenced c.1285 by Johannes Galensis (John of Wales) in Tractatus de penitentia. The demon was also said to steal monks' idle chatter and their mumbled delivery during church services to bring back to Hell. Apparently, Titivillus's work is not yet done: Marc Drogin notes in Mediaeval Calligraphy: its History and Technique (1980) that 'for the past half-century every edition of the Oxford English Dictionary has listed an incorrect page reference for, of all things, a footnote on the earliest mention of Titivillus'.
Id, p. 172, from a French manuscript, ca. 1510:
Hat tip: Eric Thomson.