The feeling you get after finishing the final book of a series or finishing the last episode of a certain show.
Symptoms may include:
• Need to re-watch or re-read
• Over fangirling/fanboying
• Excessively projecting felt love towards series via internet
• Wanting of a new installment that will surely never come
Boy: I think I have Post-series depression after watching the final episode of American Horror Story!
Girl: I felt the same way after reading the final chapter of the last Harry Potter book.