(Ἀρίστυλλος), a Greek astronomer, who appears to have lived about B. C. 233. (Plut. de Pyth. Orac. 18.) He wrote a work on the fixed stars (τηρήσις ἀπλανῶν), which was used by Hipparchus and Ptolemy Magn. Synt. 7.2), and he is undo btedly one of the two persons of this name who vote commentaries on Aratus, which are now