The Dark Shadows Alphabet Game

L is for the Lunar cycle.....which put the "Wolf" into Quentin and Chris.

M is for murderer....which is what  a trance-induced Sabrina called Alexis during a seance

Actually, in Ep #990:

Sabrina begins to moan. Who are you? asks Cyrus, are you the spirit who came to us six months ago. Let me go, she begs, twisting her head back and forth. You must help us, insists Cyrus. Let me go, she implores. She suddenly points to Alexis and says, "She's dying--can't you see, she's dying--murder, murder! MURDER!!!" Alexis collapses to the table.

N is for November - the month three of many DS fans' "favorite" actresses (Sharon Smith, Kathy Cody, and Donna McKechnie) were born. 

O is for the onyx in Barnabas' ring.

P is for poor folk...which is what Bramwell was

Q is for the many quagmires that the residents of Collinwood faced.

R is for Reds

[spoiler]Carolyn once joked that Bill Malloy was a spy for them.[/spoiler]

ProfStokes

S is for Studies...which Maggie and Vicki were always nagging David to go do.

T is for the train.

U is for Unicorn (Petofi's)

V is for vendetta.  Angelique's was probably the most prominent, but Burke's kicked off the series.

W is for Mr. Wells, the Collinsport Innkeeper.

X is for Laura Collins, Roger's eX-wife

Y is for youth, which Barnabas needed BADLY after Julia's experments on him backfired big time

Z is for zapping, which is how electric current would cause one person's life force to transfer to another.