The Tommy Westphall Hypothesis is an idea of shared univese among hundreds of television shows.
The origins of this hypothesis are rooted in Tommy Westphall.
The concept saw its first form in Six Degress of Tommy Westphall. Currently, it has grown to the rank of internet meme. The central source for adherents is The Multiverse.
Given the fame of the hypothesis, it has quite naturally gathered differing opinions. The most negative of these have created counterarguments, the most notable of which is Six Objections to the Tommy Westphall Hypothesis
Other opinions exist without denying the concept. This creates widely varying interpretations. Some reject cartoon crossovers, while others accept them under somewhat stricter guidlines. Most insist that the phenomenon be restricted to television, but a select few allow crossovers to branch through nearly all types of fiction.