Connectors, connection systems, and methods for coupling a catheter or catheter assembly to a stem of a medical device. Exemplary connectors may include a seal attached at or near a proximal end of the catheter, and a tubular housing that includes a locking member operable to connect the catheter to the medical device, preferably without the use of tools. Exemplary methods may include: inserting the stem of the device into the housing, wherein the housing is configured to press the seal against the stem, compressing the seal, and moving the locking member into a locked position.