What is Agens?

Legal Definition
Lat. An agent, a cenductor or manager of affairs. Distinguished from factor, a workman. A plaintiff. Fleta, llb. 4, c. 15, § a
-- Black's Law Dictionary
Legal Definition
A manager; a plaintiff. Agent. One who is authorized to bind his principal contractually or by representations. See 3 Am. St. Rep. 693; also Ann. Cas. 1913B, 84, and 2 L. R. A. 808, note.
-- Ballentine's Law Dictionary