It's normal to see the "blood" of extras being spilled on the Northern Ireland sets of Game of Thrones or The Fall.
But a donation drive at Crumlin Road Gaol has collected the real blood of 200 local TV and film extras.
NI's Blood Transfusion Service says it will struggle to meet its target of 8,000 new donors this year.
It says maintaining a database of 60,000 donors is integral for emergency recipients.
The event was organised to encourage new donors to come forward.
Paul McElkereney, the Northern Ireland Blood Transfusion Service's donor recruitment manager, said recruiting new donors was vital.
"Its becoming harder and harder each year," he said. "So people coming forward for the first time is absolutely fantastic.
"We need donors from across the board, people don't realise that within three-to-four days of somebody giving blood, somebody else in Northern Ireland will receive it.
"To enrol to give blood is such an easy thing to do. Seeing an advert and thinking 'I must get round to that one day' is no good."
Siobhan Hussey, a nurse who featured as an extra in locally-filmed Line of Duty, received a life-saving blood donation over Christmas 1983, after giving birth to her daughter.
"I was very tired and short of breath," she said. "I couldn't get out of bed because I was very weak and it became very apparent I'd been haemorrhaging through the night.
"I got up and collapsed and the next thing I knew, it was Boxing Night and I'd already been to theatre and received five units of blood.
"Without that I wouldn't be here to talk about it today - I'm very passionate about it.
"I've worked in A&E, so I've been part of a team giving the blood and you can see the incredible difference it can make in life and death situations.
"For a little bit of your time, you can actually give somebody a lifetime."