Electromagnetic Ghosts

When they're not tormenting humans or scaring pets, ghosts are interfering with technology, appearing on video screens, making radios and TVs crackle and playing with the lights. Alongside cold spots, E.M interference is one of the 'recognised' signs of a haunting.

Not to be confused with Ghost in the Machine. See also Haunted Technology for when the ghost is actually inhabiting the machines. This trope covers any supernatural activity that makes electrical systems malfunction as a side effect of their presence.

Please note that this often happens in worlds that do not have 'magic' as such but still have ghosts.

Examples of Electromagnetic Ghosts include:

Film

House on Haunted Hill (remake): Ghosts show up on a camcorder screen just before murdering a contestant.
White Noise is about "electromagnetic voice phenomena", where voices from beyond appear on audio and video recordings.
In The Sixth Sense, Bruce Willis's character discovers the ghosts actually exist when he can hear them on a tape recorder.
The titular Ghostbusters use a device that measures electromagnetic disruption to locate ghosts.
In one rather odd inversion from the 80s horror-comedy House (no, not that one), the protagonist sees a ghostly image of his missing child through a window. He'd been watching TV, and for no readily-apparent reason he points his remote control at the image and clicks it... at which point, the ghost-child flicks out like he's turned it off! Probably justified, as all the hauntings turn out to be the work of an old war buddy's ghost, that was messing with his head any way it could.

Literature

In Johnny and the Dead, the Dead are able to manipulate, damage, or generally mess around with radios, telephones, televisions, arcade games, jukeboxes, computer networks, satellites, and radio telescopes. Justified because one of them was an electronics genius in life, while another is Albert Einstein's distant cousin.
Tannim in Mercedes Lackey's Born to Run has a bunch of menacing-looking magical symbols covering a box he carries with him in his car. They're not really magical symbols, however, even though Tannim really is a mage: the symbols came from a Led Zeppelin album, and he's using them solely to scare away ghosts who might otherwise get too close and unintentionally wipe the music collection he keeps in that box. It works, although he mentions that the ghosts of metal-heads aren't intimidated, but give him a high-sign and say, "Duuuude!"

Live Action TV

In Supernatural normally invisible ghosts show up on camcorder screens and EMF detectors are used by ghost hunters.

Tabletop Games

Geist: The Sin Eaters affords ghosts several Numina that allow them to do this, such as Ghost Sign (imprint a message in a medium) or Left-Handed Spanner (make technology go haywire). As such, several Sin-Eaters have necromantic Ceremonies that rely on these tropes, like Spectral Photography (take a photograph of an area, get a glimpse of the most dynamic ghost activity that happened in the last few days) and Dead Voices on Air (leave a specially-prepared camera behind, and it will capture whatever ghostly activity occurs in the meantime).

Theater

Depending on the production, the ending of Blithe Spirit as ghosts Elvira and Ruth destroy the house.

Urban legends and 'real' life.

E.V.P(Electronic Voice Phenomena)- anomalous voices or other sounds on electronic audio recordings.

Video Games

In F.E.A.R., your radio crackles and "unknown origin" is shown as the transmission source in response to supernatural events. Alma also appears on monitors occasionally.
- In FEAR 3 Alma's contractions cause an EMP like effect.
While most supernaturalness in Dead Space and Dead Space 2 is inside Isaacs head something is interfering with RIG transmissions.
Many of the powers in Ghost Master are electrical in nature such as blow fuse,blackout, wild and crazy and strange behaviour. Technology is also one the 'fetters' or places ghosts can be anchored.
The original Silent Hill had a radio which gave off static in the presence of monsters.
- In Silent Hill: Shattered Memories, you can only see ghosts by looking at them with Harry's cell phone camera, and "echo memories" (which are sort of... lingering traces of emotionally-charged events?) cause the phone to give off weird static/feedback.
In Sengoku Basara 3, Oichi has a similar "static effect" sometimes when she speaks, in a reference to this phenomenon.
Taping EVPs and snapping photos of ghosts is a crucial part of The Lost Crown: A Ghost-Hunting Adventure.
Rotom from the Pokémon series.

Web Original

The Slender Man is often shown to muck up electronic equipment, causing static, audio and visual distortion, missing frames, added frames, and general horror. A video camera is also a way to see him when he is otherwise invisible.
And as we've seen in Marble Hornets, trying to film him tends to make it worse. * Jay Are's backpack in The League of STEAM is supposedly a device for picking up EVPs.

Webcomics

The webcomic Chainsawsuit plays with this in one of their panels, where the ghost in question is the ghost of an old bunny-eared TV set spouting static.