STILBE was the Naiad-nymph of the spring, well or fountain of the main town--possibly Gyrton--of the Lapithai (Lapiths) in Thessalia (northern Greece). She was loved by the god Apollon and bore him Lapithes, the eponymous first king of the tribe, and some say Kentauros (Centaurus), who mated with mares to produce the tribe of Kentauroi (Centaurs).
 LAPITHES, KENTAUROS (by Apollon) (Diodorus Siculus 4.69.1)
STILBE (Stilbê), a daughter of Peneius and Creusa, became by Apollo the mother of Lapithus and Centaurus. (Diod. iv. 69; Schol. ad. Apollon. Rhod. i. 40.)
Source: Dictionary of Greek and Roman Biography and Mythology.
CLASSICAL LITERATURE QUOTES
Diodorus Siculus, Library of History 4. 69. 1 (trans. Oldfather) (Greek historian C1st B.C.) :
"He [the river-god Peneios (Peneus)] lay with the Nymphe named Kreusa (Creusa) and begat as children Hypseus and Stilbe, and with the latter Apollon lay and begat Lapithes and Kentauros (Centaurus)."
Diodorus Siculus, Library of History 5. 61. 3 :
"Lapithes, the son of Apollon and Stilbe, the daughter of Peneios (Peneus)."
- Diodorus Siculus, The Library of History - Greek History C1st B.C.