Need an undead encounter

I need a dnd encounter for my level 1 party, that isn't the final boss.

It needs to be creepy

Not to hard for the party, it's their first dnd session ever

Would make more Sense in my campaign to have 2 of them.

This party contains 6 members btw

Perhaps a Specter with 3 skeleton minions. Have it on a haunted farm and the Specter be a disgruntled farmer.

A Poltergeist that's loose in a library could work if you have 6 players.

Perhaps a Spy that's been sneaking zombies into the town via smuggling tunnels