When a character has to get through glass, they cut out a perfect, round hole while leaving the rest of the panel untouched. It's a stealthier, quiet alternative to smashing the glass. It creates a larger opening than drilling a hole would, at least large enough that the character can reach inside.
If the person breaking in is prepared, they will have a device specifically designed for this purpose. It's a suction cup with an attached lever, with a cutting element — such as a diamond or laser - on the end of the lever. The suction cup is applied to the glass, then the lever is moved around in a circular motion, cutting a circular area out of the glass.
If a character doesn't have such a device, they will improvise by using the sharp point of a diamond ring instead. Another common variation is the use of sharp claws, in which case the circle is cut freehand.
In real life, this is not possible. MythBusters tested and busted it during one of the "Crimes and MythDemeanors" episodes. To cut out a circle, a glass cutter puts an even scratch (or score) on the glass. In order to get a controlled break along the score, force needs to be applied on both sides of the glass. If a burglar could reach the other side, they wouldn't need to cut a hole. The laser examples do escape those problems but run into the logistics of how much juice a laser needs to be strong enough to cut glass or how they don't overdo it.
- Averted in the Gunsmith Cats manga, where a criminal is able to break into Bean Bandit's car by cutting a jagged, uneven scratch on the bulletproof window with a glass cutter and firing her gun repeatedly on it, until it cracks off the edges of the scratch.
- Happens in the Magic Kaito manga, in the opening sequence of chapter 4, "Kaitou Kid's Busy Day Off". Removed from its first animated adaptation in the second Magic Kaito special, the scene is reinstated in the second animated adaptation, in episode 7 of the Magic Kaito 1412 anime.
- A variation in The Great Mouse Detective. Basil and Dawson trail Fidget to a toy shop he broke into. Basil sees a hole drilled into the window—a small hole, the size of a single finger—and immediately realizes that's how Fidget got in. Dawson wonders how anyone could fit through such a tiny hole. Basil demonstrates by popping Dawson's finger into the hole, then using that finger to pull the window open on its hinge.
Dawson: Basil, you astound me!
- In Ponyo on the Cliff by the Sea, the title character tries to escape from her dad's house by using magic to cut a hole in one of the house windows. But because the house is underwater, this leads to loads of water coming through the window and Ponyo gets caught in the flow of water instead.
- In Shrek 2, Puss in Boots cuts a circular hole with his claws to get the "Happily Ever After" potion from the Fairy Godmother's storage room. The hole, however, turns out to be too small for the bottle to fit through, and Puss ends up pulling the bottle so hard that the glass pane shatters.
- In the climax of The Assignment (1997), a KGB commando team is assaulting the safehouse of Carlos the Jackal. In this instance the cut is made by a fast burning fuse around the rim of the sucker clamp.
- In the 1959 film adaptation of The Bat, the title murderer uses a small blade to cut a hole from a glass-paned door, which he then unlocks and opens by reaching inside.
- Funny moment in the Italian comedy Bingo Bongo when the titular character used his sharp nails to cut through the glass window of a restaurant in order to snatch food from a table inside. Watch the scene here.
- In the 2000 live-action adaptation of How the Grinch Stole Christmas!, the Grinch cuts an enormous hole in a plate-glass window with his sharp fingertips. And instead of using a suction cup device to remove the cut-out piece, he sucks on the glass with his mouth.
- Hudson Hawk: While breaking into the auction house, Eddie uses a suction cup device to cut out a hole in a glass door. It's large enough that he and Tommy Five-Tone can slip inside.
- Mission: Impossible
- In Mission: Impossible II, Ethan Hunt laser-cuts a hole through glass and jumps through into the lab.
- In Mission: Impossible Ghost Protocol, Ethan has to enter a room in the Burj Khalifa from the outside. His laser glass cutter malfunctions though before he can finish cutting the hole and he has to break the glass with his feet to get into the building.
- Undercover Brother. Played for Laughs when Undercover Brother breaks in through a window. He slices a circle in the window and then taps on it. This causes the entire rest of the window to shatter, leaving the cut-out circle intact.
- In The Mad King by Edgar Rice Burroughs, the hero cuts a circular hole in a window using a diamond ring borrowed from the heroine.
- Red Dragon. The forensic investigators establish that the Serial Killer used one of these to enter a glass door because, rather than a perfect circle, it forms an egg-shaped cut because the string shortens as it winds around the handle of the suction cup. The fact that he brought such a burglary tool in the first place turns out to be an important clue.
- Older Than Television: Sherlock Holmes does this in Arthur Conan Doyle's short story "The Adventure of Charles Augustus Milverton", 1904. In the words of Dr. Watson: "The place was locked, but Holmes removed a circle of glass and turned the key from the inside."
- The Stainless Steel Rat does this when breaking into an Inland Revenue office complex to wipe his and Angelina's tax record clean. At one point he is poised on a very narrow windowsill manipulating a glass cutter and a suction disc, so as to be able to remove the glass circle cleanly without triggering any alarms.
- In the 1960's Batman episode "The Purr-Fect Crime", Catwoman uses her glove/claws to carve a hole through a museum display case.
- In one Leverage episode, Parker cuts a glass pane on a bomb they're trying to disarm using a diamond she kept from their last heist.
- In one arc of Mission Top Secret, Neville Savage and his Accomplice of the Week uses a glass cutter to steal a vase from a museum. However, the hole is far too small so he ends up having to break the glass case anyway.
- Broken Sword:
- Broken Sword: The Shadow of the Templars: In the opening cutscene of the Director's Cut, the killer gains access to his victim's place by using a glass cutter on the balcony window.
- In Broken Sword: The Serpent's Curse, George cuts the window in Henri's office using the engagement ring he found in the safe.
- Call of Duty: Ghosts: A laser-powered item called the Glass Cutter appears exclusively for the level "Federation Day," where it is used to break in through the building's windows.
- Henry Stickmin Series; In Stealing the Diamond, Henry attempts to use a laser cutter to get the aforementioned diamond out of its case. It jams before swinging wildly, slicing Henry in half in the process.
- Chris Fisher's illustrated fanfic Of Mice and Mayhem has the Rescue Rangers use a sharpened stylus to cut an access hole in the window of a research laboratory in an effort to rescue Gadget and other small critters caged there. Defeated when one young mouse, eager to be helpful, opens the window lock, which triggers an intrusion alarm.
- Batman: The Animated Series used this one a bit. Catwoman does this with her claws twice in her introductory episode; the first time, she cuts a small hole for her cat, Isis, to climb through. Batman does this with one of his batarangs. And in "Harley and Ivy", Harley Quinn starts to use a circle cutter on a glass case in a museum — but Poison Ivy accidentally triggers a different alarm in the same museum, so Harley just smashes the case.
- The Legend of Korra: Ming-Hua can do this entirely with her waterbending: cutting a circular hole in the glass with the tip of a cutter made of ice, and using her watery arm as the suction cup.
- Looney Tunes: "Beanstalk Bunny" sees Bugs and Daffy trapped inside a transparent tureen. Just when it looks as though Daffy's efforts to get through to Bugs have failed, upon which he resigns himself to the same pose to await his fate, Bugs produces a pocket glass-cutting device and leaves two character-shaped holes for Elmer the giant to view in his dinner preparations.
- My Little Pony: Friendship Is Magic: In "Sparkle's Seven", Spike cuts a round hole through a stained glass window in the Canterlot Castle throne room with his claw so he and Fluttershy can sneak in.
- When Rick and Morty go to a HeistCon convention, they discover this method is the only way to get in. Rick is less than amused.