If you're ever asked what's the brightest star in Orion, the answer is invariably Rigel – which is (normally) the sixth brightest star in the night sky. But as mentioned on the main Brightest Stars page, Rigel's astronomical name is not Alpha Orionis; it's Beta Orionis. This is because there are two First Magnitude stars in Orion, the other one being Betelgeuse. Since the latter is at the "top" (it forms the right shoulder of the figure, or the left one as you look at it) and Rigel is at the bottom (it's the left foot, or the right one as you look at it), it was Betelgeuse that got the Alpha designation.
In fact it's even more complicated than that, because Betelgeuse is a variable star, and occasionally it is brighter than Rigel. It's a quizzer's nightmare!
If you get asked any other question about a star in Orion (i.e. other than "What's the brightest star in Orion?"), and there is any doubt, the safest option is usually to go for Betelgeuse – it's the one that people can remember because it's got a funny name.
© Haydn Thompson 2017