A device for successively feeding stacked packages to a machine for manipulating and/or treating and/or processing the packages, comprising: - a hopper for containing a stack of packages according to such an arrangement that the stack of packages extends along a reference axis, wherein the hopper comprises an outlet for letting the package at the bottom of the stack exit; - a singularizing member for separating the package leaving the hopper with respect to the remaining packages of the stack; - a member for receiving a single package leaving the hopper, which is provided with a seat for housing the package, the seat being located on a plane parallel to the plane (P 1) of the outlet of the hopper, and arranged so that it is not coincident with the outlet of the hopper, wherein the receiving member defines a position for the package to be picked up and transferred to the machine; wherein the singularizing member is arranged between the outlet of the hopper and the receiving member, and is provided with an opening (6A; 6A') for the passage of a single package leaving the hopper, wherein the singularizing member is, furthermore, rotatable around a rotation axis parallel to the reference axis, between a receiving position, in which the opening (6A; 6A') is arranged to be coincident with the outlet of the hopper, for receiving the package leaving the hopper, and a releasing position, in which the opening (6A; 6A') is arranged to be coincident with the seat of the receiving member, for releasing the package that has left the hopper into the seat of the receiving member; the device being characterized in that the singularizing member has one or more helical surfaces (62, 63), which delimit the opening for the passage of the package, to exercise an accompanying and guiding action on the package, for moving the package along the reference axis, during rotation of the singularizing device from the releasing position to the receiving position. - a hopper for containing a stack of packages according to such an arrangement that the stack of packages extends along a reference axis, wherein the hopper comprises an outlet for letting the package at the bottom of the stack exit; - a singularizing member for separating the package leaving the hopper with respect to the remaining packages of the stack; - a member for receiving a single package leaving the hopper, which is provided with a seat for housing the package, the seat being located on a plane parallel to the plane (P 1) of the outlet of the hopper, and arranged so that it is not coincident with the outlet of the hopper, wherein the receiving member defines a position for the package to be picked up and transferred to the machine; wherein the singularizing member is arranged between the outlet of the hopper and the receiving member, and is provided with an opening (6A; 6A') for the passage of a single package leaving the hopper, wherein the singularizing member is, furthermore, rotatable around a rotation axis parallel to the reference axis, between a receiving position, in which the opening (6A; 6A') is arranged to be coincident with the outlet of the hopper, for receiving the package leaving the hopper, and a releasing position, in which the opening (6A; 6A') is arranged to be coincident with the seat of the receiving member, for releasing the package that has left the hopper into the seat of the receiving member; the device being characterized in that the singularizing member has one or more helical surfaces (62, 63), which delimit the opening for the passage of the package, to exercise an accompanying and guiding action on the package, for moving the package along the reference axis, during rotation of the singularizing device from the releasing position to the receiving position.