In order to be classified as a waifu, the entity in question must be a fictional character, i.e. one who is not known to reside in what we perceive as reality. Assuming they meet this criterion, it is up for debate as to whether the entity must also have been produced through physical or digital animation. Some claim that only 2-dimensional characters can be waifus, but this view disregards all anime that have been produced using 3-D simulation techniques. Others say that any animated character can be a waifu regardless of dimensionality, but characters being portrayed by real human beings (such as in the Star Wars movies, or a live-action anime adaptation) cannot. Then there are those who hold neither position, and simply identify characters from any fictional medium as potential waifus. It's a pretty hotly debated topic in the anime community.
@JazzMan1221 Yendor from the japanese webcomic adaptation of lost stars for best girl Ciena Ree for cutest officer under Darth Vader.