Matanbuchus

Matanbuchus - in The Martyrdom of Isaiah, Testament of Job, and in the Introduction to The Ascension of Isaiah, Matanbuchus is referred to as the angel of lawlessness, and identified with Beliar: "Beliar, whose name is Matanbuchus."  The name is believed to be composed of 2 Hebrew words: mattan buka, meaning "worthless gift"; or, better, a form of the Hebrew mithdabek, "one who attaches himself," i.e., and evil spirit. (a)

Resource List - all entries are taken verbatim from the original source:

(a) "The Dictionary of Angels" by Gustav Davidson, © 1967