A spill-proof beverage dispenser comprising: (a) a container adapted to at least partially define an interior volume available for occupation by a liquid; (b) a lid adapted to be mounted to the container, the lid including a vent and a dispensing opening, and a liquid conduit having a passageway therethrough in fluid communication with the liquid within the container and selective fluid communication with the dispensing opening; and (c) a valve assembly mountable to the lid including a collapsible tower adapted to be received at least partially within the liquid conduit to selectively restrict liquid flow between the interior volume of the container and the dispensing opening, the collapsible tower being responsive to changes in pressure by collapsing at least one wall of the collapsible tower to selectively provide fluid communication between the passageway and the dispensing opening.