There is a long-standing belief in popular culture that actors are shorter than the national average. I decided to put the theory to the test, creating a spider to scrape height data for the top 5,000 ranked actors and actresses on IMDb. It turns out: actors and actresses - by IMDb height - are two inches taller than the national average.
Heights of the Top 500 Actors and Actresses as Ranked by IMDb's "Starmeter."
The top 500 actors average 5 foot 11.7 inches versus the national male average of 5 foot 9.5 inches. The top 500 actresses average 5 foot 5.72 inches versus the national female average of 5 foot 4 inches. The trend holds for the top 1,000 actors and actresses, as well as the top 5,000.
The easiest explanation is that both actors and actresses are finding ways to over-report their heights on IMDb on a massive scale. However, when I spot-checked a list of famously short actors and actresses, I found no discrepancies between IMDb's numbers, and celebrityheights.com. Granted, I'm not sure how to rigorously fact check 5,000 IMDb actor heights.
If actors are over-reporting their heights, it is worth noting they are no different from the rest of us. OKCupid found their users report heights two inches above the national average.
The alternative explanation is that successful actors are simply taller. This success/height correlation should make some sense given the data that taller people are smarter, earn more money, and are more respected by their peers, than short people (I am not a particularly tall person, so I write this without any bias).
The real upshot is, there is no data to support the idea that actors and actresses are shorter than average. In fact, the more popular an actor is, the more likely he is to be tall (actresses, on the other hand, retain a constant height regardless of popularity).
Methodology: Because certain minority groups may be underrepresented in the top 5,000 actors, the charts above compare actors to the average height for American Caucasians.
For my data set, I parsed out actors and actresses under 18, as they may not yet have achieved full height.