Here is a list of all the "popular" series I've finished and need to finish from YA to NA and Adult.
FINISHED SERIES
- Starcrossed trilogy
- Daughter of Smoke & Bone trilogy
- The Mortal Instruments series
- The Lunar Chronicles series
- Under the Never Sky trilogy
- Mara Dyer trilogy
- Fifty Shades trilogy
- Shatter Me trilogy
- Amulet series
- Legend trilogy
- Lords of the Underworld series
- Splintered trilogy
- Under the Never Sky trilogy
- The Syrena Legacy trilogy
- Lux series
- Penryn and the End of Days trilogy
- Runes series by Ednah Walters
UNFINISHED SERIES
- Throne of Glass series
- A Court of Thorns and Roses series
- The Selection series
- Percy Jackson series
- The Coincidence series
- The Murder Complex trilogy
- The Dark Elements trilogy
- Delirium trilogy
- Ruby Red triolgy
- The White Rabbit Chronicles
- Anna & the French Kiss trilogy
- The Diviners trilogy
- Burying Water series
- The Grisha trilogy
- The Iron Fey series
- Remnant Chronicles by Mary E. Pearson
- Beautiful Bastard series
- The Young Elites trilogy
- Crossfire series
These are all series including 3 or more books. I'm not including duologies.