Is Billy A in Pretty Little Liars?

Answer 1

No.

**SPOILERS**

Alison is A, her twin sister, Courtney, pretended to be Alison during seventh grade. She is dead, killed by Alison. Alison read her diary and was A during the fifth, sixth, seventh and eight book.
No billy is not -A

If you don't want to find out who -A is read No further

Alison Dilaurentus has a twin Courtney Dilaurentus who has mental issues and is held captive at at mental institution and when she come home for a weekend she tricks alison into swapping lives with here as they are identical. so alison is sent back to mental institution instead of courtney and then courtney dumps ali's old friends and recruits Spencer, Aria, hanna, and emily to be her new friends. and then alison gets mad for being locked away so she torchures courtney and becomes -A she also kills courtney and starts to torchure the liars (emily, spencer, aria, and hanna)

Hope This Helps