A woman has been arrested on suspicion of causing death by dangerous driving after a collision between two cars.
Passenger Ellie Bryan, 18, died in the crash on the A487 at Comins Coch, near Aberystwyth, in Ceredigion on Saturday night.
The driver of the Vauxhall Astra remains in a critical condition.
Police inquiries found a third car was involved, the 18-year-old driver of which has been arrested and released on bail.
Ellie's family said in a statement: "We are distraught by our loss of Ellie. She will be missed by us all.
"Ellie was a loving daughter, sister and granddaughter.
"We would like to thank everyone for their support at this devastating time."
Dyfed-Powys Police has appealed for witnesses and anyone with dashcam footage to get in touch.