I used the following node setup in the compositor to solve the problem I was experiencing:
The general gist of what the nodes are doing is creating an ellispe with the "Ellipse Mask" node and shaping it as necessary with the width and height parameters.
Next, I feed the Mask output of the Ellipse Mask Node to the Invert node. When initially using the Ellipse Mask node, the colors were opposite of what I desired, so the Invert node solves that problem with no required configuration of the node.
I feed the Color of the Invert node to a Blur node, ensure the "Gaussian" method is selected from the drop down list, and configure the parameters until I am comfortable with the blur or feathering of the Ellipse mask used at the beginning.
I then feed the Image output of the Blur node to an Alpha Over node, combining it with the original image as well as black in order to "fade to black" and bing-bang-boom, why's your mother in your room?