A catheter and methods are provided for inserting at least portions thereof into a vessel, cavity, or tissue of a human body to thereby provide manipulation of a distal portion of the catheter when positioned within a vessel, cavity, or tissue. The catheter preferably has a module which includes an elongate tube having at least one lumen extending from a distal end to a proximal end of the tube, a module interface connected to the proximal end of the tube, and a deflector connected to the tube for deflecting the distal portion of the elongate tube. A handle detachably connects to the module and is configured to be readily held in the hand of a user. The handle has a body which includes a wall positioned in and extending transversely across distal portions of the body. The wall has an outer surface thereof defining an exterior portion of the body and a first cavity formed within the body. Preferably, the body detachably and coextensively connects to the module interface through the outer surface of the wall. A controller is connected to the body and detachably connects to the deflector of the module for responsively controlling the deflector to thereby manipulate distal portions of the elongate tube. The controller and the deflector connect to define a unitary catheter manipulator extending from the first cavity, through the wall, and to the tube for manipulating a distal portion of the catheter when positioned within a vessel, cavity, or tissue.