Title says it all: when you first encountered a DC comic book character named either "Doctor Mid-Nite" or "Doctor Midnight", which one was it?
Dr. Charles McNider - first appeared 1941 / death in 1994
Dr. Beth Chapel - first appeared 1985 / death in 1993
Dr. Pieter Cross - first appeared in 1999
Remember, this poll is who you first read about, not which one you prefer.