The one who: -(y)an

Turkish has no relative word like who or that. To say the man who is waiting, add -an / -en to the verb stem and put it before the noun: bekleyen adam (the man who is waiting).

• After a, ı, o, u: -an (kazanan, oturan); after e, i, ö, ü: -en (gelen, bilen).
• After a vowel, add y: oku → okuyan, bekle → bekleyen.
• Negative: -mayan / -meyen: bilmeyen (who doesn't know), gelmeyen (who didn't come).
• In etmek and gitmek the t becomes d: eden, kaybeden, giden. Most other verbs keep it: satan, atan.

The form covers present and past; context decides. Without a noun it means the one(s) who: gelenler (those who came), bilen var mı? (does anyone know?). For who will, use -acak / -ecek instead.