Ghosts and ghouls of the dress-up variety will be out in force this weekend, but in some cases, things that go bump in the night aren't just a Halloween special.
Haunted for several hundred years, Ross Castle in Co Cavan attracts paranormal investigators from all over the world.
Dating back to the 16th century, the castle is currently run as a B&B by Benita and Sam Walker.
"Ross Castle would be very well known internationally as a haunted castle, and we get a lot of groups from different places coming to the castle with their equipment. For some of them, it's just a bit of fun. Others take it very seriously," explains Benita.
The castle was built in 1536 by Richard Nugent, the 12th Lord of Delvin. His daughter Sabina fell in love with the son of a local Irish lord who was an enemy of Nugent's.
Knowing their love was doomed, the couple attempted to elope. But crossing the lake in a boat, a storm blew up and the young man drowned. Sabina was rescued but when she woke up and discovered her lover was dead, she was inconsolable. She died shortly after and according to Benita she is still waiting for her lover.
"There's nothing evil about it, and I have never seen her, although my children have. Occasionally taps come on for no reason. There are some cold spots which cannot be heated; doors open by themselves and I've heard footsteps when there is no-one there, but it's not a bad feeling," explains Benita, adding that they don't live in the castle.
"We live nearby, so we leave the guests and the ghosts to themselves," she laughs.
But it's not just the ghost of Sabina Nugent that wanders around Ross Castle says Benita.
"Over the years dozens of spirits have been detected here and many of them have been cleared, but we're hanging onto Sabina. She's part of the castle and she's good for business," adds Benita.
Breda Duggan of Ghosthunters Ireland says Ross Castle is one of the most popular places she brings groups to, and they are having a 'ghost hunt' there tomorrow night.
"A few people get scared and want to leave, but generally it all goes well. Spirits aren't harmful. Sometimes they just become frustrated and they want to let you know they are there, which is why they bang doors or turn on lights," says Breda.
In Kinnitty Castle, Co Offaly, plans are also afoot for a spot of ghost hunting this weekend. UK paranormal historian and presenter of Living TV's 'Most Haunted', Richard Felix will give a talk on paranormal activity, followed by a mass séance at the nearby stone circle, and a visit on Saturday to Leap and Charleville castles, both in the haunted triangle in Co Offaly.
The event will round off with a Halloween ball and some ghost hunting.
"Kinnitty Castle is part of what is known as the haunted triangle in this part of the country," explains Gillian Pierce, Marketing Manager at Kinnitty.
"There is on-going interest from paranormal investigators about the ghosts in the castle, all of which are harmless.
"The Geraldine Room is haunted and staff often hear the sound of a little girl playing and laughing, which is said to be the ghost of a child who died here in the past," says Gillian.
"We are inundated with requests for the Geraldine Room. If anything, guests are attracted by the fact it's haunted.
"Sometimes nothing happens, but other times guests tell us they heard strange sounds. Staff and visitors have also seen the phantom monk who haunts the banqueting hall," she adds.
But while the odd friendly ghost wandering about a hotel or B&B can help owners to make a killing, an un-wanted presence in the house isn't everyone's idea of spirited fun.
Medium and healer Philip Sutcliff of the Whole Spectrum Healing Centre in Gorey, specialises in 'spirit clearances', although his main work is in the area of healing.
"Occasionally I am asked to look at a particular house where there is something happening that is beyond the owners knowledge, a situation where they feel there is something disturbing them," he explains.
"Spirits can be present in a home or building of any age. If a property is close to an underground stream and high voltage electricity, it can be easier for spirits to make contact," he adds.
Other Irish haunted homes including Woodlawn House in Galway, and Seaforth House in Co Sligo, remain unoccupied and abandoned by all but the spirits.