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Beta Cephei (β Cephei, abbreviated Beta Cep, β Cep), also named Alfirk, is a third magnitude star in the constellation of Cepheus. It is the prototype of the Beta Cephei variable stars.

Alfirk is visible primarily in the northern hemisphere, given its extreme northern declination of 70 degrees and 34 minutes.  The WGSN approved the name Alfirk for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.

β Cephei is a triple star comprising a spectroscopic binary with a magnitude 8 optical companion. Its magnitude varies between +3.16 and +3.27 with a period of 0.19048 days.

β Cephei A is a blue giant star with a stellar classification of B1 IV. It has previously been classified with either a main sequence or giant luminosity class.[13] This star has a radius that has been estimated at 6 Ro and a mass of 12 Mo. Like most high-​mass B-​class stars, β Cep is a relatively young star with an estimated age of just a few million years. Like the majority of giant stars, β Cephei A rotates slowly on its axis with a rotational velocity of 7 deg/day, a speed which takes the star approximately 51 days to make one complete revolution.

β Cephei B is a Be star in an 85-year orbit with the giant primary. It has been resolved using speckle interferometry at a distance of 0.25" in 1972.

β Cephei C is a magnitude 7.8 A2 main sequence star 13.6" distant.