The name Buffy is a girl's name . Buffy and is often added to lists like Nicknames for Elizabeth and discussed in our forums with posts like "The Makeover Baby Name Game".
From the experts:
Buffy was a one-time sorority girl with a roommate named Muffy, then a fearless vampire slayer, though still basically fluffy. You might think of Buffy as the feminine version of Chip or Bud -- an all-purpose nickname now buried in a mid-century time capsule.