In Mercedes Lackey 's Born to Run (part of the Serrated Edge series), due to participating in a magical battle while exhausted (his aim goes to pieces when he's tired), Tannim accidentally gave an elf a 'Reverse Mohawk' because his magic bolt riccoheted off and cut a clean line along his scalp. The elf kept this style for the rest of the book, despite their glamour magic.
In Finder's Stone trilogy one halfling got a clump of her hair shaved off by dozen of sweeping disintegration rays. Granted, this trap was set on a reasonable assumption that only one human could be there, but it still looks like those who suspected she's favoured by Lady Luck even more than other halflings got it right...
During a duel Harry ducks to avoid a spell, and mentions the smell of singed hair to show how close the spell was
In the Italian children's book Il Mascheraio Innocente (The Innocent Mask-maker), the titular character is wrongly accused of putting a wasp inside a duchess' mask, and sentenced to death by beheading. He spends the time until the execution making a mask with his likeness and then wears it on top of his head, so when he gets executed he survives. He didn't make the neck of the mask quite long enough, though, causing his friends to remark that "[his] haircut looks like it's been made with a meat cleaver".
In the Federation of the Hub story "Lion Loose", "Baldy" Perk got his name because a near-miss from a blaster permanently removed the hair from the top of his head.
During Galaxy of Fear, Zak gets attacked by a gardening droid and ducks in time to avoid being bloodied by its shears, but it still clips a hank of hair from the top of his head.
The climax of The Bride of Newgate by John Dickson Carr, set in 1815, is held up by the arrival of a minor character at Darwent's house, demanding satisfaction for mostly plot-irrelevant issues. Darwent and everyone else (including the reader) is impatient to go on with the plot, but as the intruder is An Officer and a Gentleman he can't refuse the duel. Riled, but not wanting to kill or seriously injure the man, Darwent (who, before being made a peer, was a fencing master) shaves off some of his hair and both of his impressive and stylish sideburns. Then his maddened opponent accidentally charges through a false wall, revealing the hidden room that holds the central mystery and kick-starting the climax proper.
In Thief of Time a monk ducks an axe swing from an Auditor, but his much beloved ponytail is sliced off in the process. Things then proceed to go very badly for the Auditor.