It turns out that Shaun of the Dead's bald "vinyl" zombie doesn't deserve much sympathy, despite having chunks of Sade's "Diamond Life" lodged in his head. When Simon Pegg's Shaun and Nick Frost's Ed wake up hungover after a night at the Winchester, their first indication that something's amiss is undead Mary loitering in the backyard. She's soon joined by a large male zombie, resulting in the famous "vinyl" scene where Shaun and Ed toss records at the slow-moving intruders, before eventually resorting to the more effective cricket-bat-and-spade combo.
Though not revealed in the film itself, these two Shaun of the Dead zombies share a backstory far more sinister than you'd expect from the 2004 rom-zom-com classic. To promote Shaun of the Dead's release, Simon Pegg co-wrote a comic strip prequel with director Edgar Wright, which released in 2000AD (the comic company, not the year). Sadly, the prequel flew largely under the radar for anyone who wasn't already a fan of Wright, Pegg and Frost's work in Spaced. Starting prior to Shaun of the Dead and continuing into the opening act, the comic is told through the perspective of Mary before she was zombified.
The prequel begins with Mary serving an inattentive Shaun at a grocery store. The customer after Shaun, however, is the same large, bald character who later gets pelted with vinyl - but the stranger is far scarier in life than as a member of the undead. When Mary's shift is finished, she leaves work, only to be followed by the unnamed man, forcing Mary to take refuge inside the nearest pub - the Winchester. Sitting with one of the "rich and interesting" regulars the same night Shaun and Ed are getting hammered, Mary eventually leaves the Winchester, only to be bitten by the patron she was drinking with moments earlier.
Infected and bleeding, Mary lies motionless on the sidewalk. The bald creep from the grocery store emerges, having waited for Mary outside the Winchester, and as he moves to assault the prone young woman, she lurches into life and bites him in the mouth. A boozed-up Shaun and Ed then walk past loudly singing disco classics, and both zombies follow the noise toward Shaun's garden.
The backstory behind Mary and her attacker completely changes how Shaun of the Dead's vinyl scene is viewed. Audiences might've initially felt sympathy for the hapless wanderer Shaun deems unworthy of wasting a Stone Roses record on, but knowing the man only became a zombie because of an attempted sexual attack makes Shaun and Ed's beating feel somewhat like retribution. On the other hand, Mary becomes a more tragic figure. It's hard not to laugh along with Pegg and Frost when the shop assistant gets impaled on a washing line post, but knowing her past removes all humor from the situation.
The Shaun of the Dead prequel comic also includes some fascinating moments of movie continuity. When the vinyl zombie first appears in Shaun of the Dead, his mouth is all mangled; the comic helpfully explains why, with Mary herself dealing the damage. More importantly, Shaun actually could've prevented the entire ordeal. When young Mary is first being chased, she bumps into Shaun before heading into the Winchester, and attempts shouting after him for help. Shaun obliviously walks on, paying the calling woman no mind. Had Shaun not been distracted by the thought of Strawberry Cornettos (probably), he could've helped Mary, she wouldn't have gone to the pub and been bitten, the bald creep wouldn't have attacked her, and neither of them would've ended up in Shaun's backyard - a perfect example of how Shaun's life would be better if he weren't so apathetic.