In this paper, we introduce and study the essential pseudospectra of closed, densely defined linear operators in the Banach space. We start by giving the definition and we investigate the characterization, the stability and some properties of these essential pseudospectra. Mathematics Subject Classification 47A53 • 47A55 • 54B35 • 47A13 1 Introduction Let X and Y be two Banach spaces. We denote by L(X, Y) resp., C(X, Y) the set of all bounded (resp., closed, densely defined) linear operators from X into Y and we denote by K(X, Y