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Karl pulls an injured Ben along, after being captured by the Losties in ("Through the Looking Glass, Part 1") (promotional still).

The characters in Lost are often literally or symbolically forced to deal with imprisonment, both on-Island and in their pasts.

Literal imprisonment

The following characters have been shown off the Island literally behind bars or in custody.

		Location
	Desmond	Southway Garrison prison
	Jack	Local jail
	Kate	Custody of U.S. Marshal
	Sawyer	Federal prison
	Sayid	Imprisoned during war Interrogated by CIA
	Hurley	L.A. County Jail
	Richard	Prison in Tenerife

The following list shows when any characters have literally been imprisoned.

Kate was in federal custody overseen by U.S. Marshal Edward Mars. ("Pilot, Part 2")
Nadia was held prisoner by the Iraqi Republican Guard, and was questioned by Sayid. ("Solitary")
After following the cable, Sayid was captured and held prisoner and tortured by Danielle Rousseau in her camp. ("Solitary")
Ethan took Charlie hostage for the objective of helping his kidnapping of Claire. ("All the Best Cowboys Have Daddy Issues")
Kate, Six Foot Five, Jason, and Baseball Hat robbed a bank, taking Mark Hutton and the customers of the bank hostage. ("Whatever the Case May Be")
Hurley was committed at Santa Rosa Mental Health Institute. ("Numbers")
Sayid was imprisoned during the war. ("The Greater Good")
Walt was captured by Tom and the Others for their own reasons. However later Walt served as a hostage when Ben was held by the survivors, and Michael was captured by the Others: Walt was leverage for the Others to convince Michael to free Ben. ("Exodus, Part 2") ("Three Minutes")

Desmond took John Locke hostage at gunpoint (and Kate prisoner) as leverage when Jack entered the Swan armed. ("Man of Science, Man of Faith")

Ana Lucia used the tiger pit to first imprison Nathan, and then the raft group (Michael, Sawyer, Jin). ("The Other 48 Days") ("Orientation")
Sayid was taken prisoner by the Tailies after he attacked Ana Lucia. ("Collision")
Eko was taken prisoner as a child by the thug captain ("The 23rd Psalm")
The castaways imprisoned Ben. ("One of Them")
Sayid and Tariq were held by U.S. forces in Iraq. ("One of Them")
Michael was imprisoned at the Others fake camp. ("Three Minutes")
Desmond was in Southway Garrison after "failing to follow orders". ("Live Together, Die Alone")
Bea Klugh, Tom, Ben, and the Others took Jack, Kate, and Sawyer hostage both for their own reasons, as well as for warning the Losties to stay away from their side of the island through a message sent by Hurley. ("Live Together, Die Alone")

Sawyer met Karl, who was also imprisoned by the Others. ("A Tale of Two Cities")
Jack was arrested for assaulting his father, but was bailed out by his estranged wife. ("A Tale of Two Cities")
Jack, Kate and Sawyer were imprisoned by Ben, Juliet and the Others on Hydra island. ("A Tale of Two Cities")
Sawyer and Kate were forced to work a day-shift there in the Quarry. ("The Glass Ballerina")
An unconscious Eko was confined within the polar bear cave. ("Further Instructions")
Sawyer was imprisoned for a con job. ("Every Man for Himself")
Karl was held prisoner in Room 23. ("Not in Portland")
Juliet was imprisoned by the Others for killing Pickett. ("Stranger in a Strange Land")
Sayid was held by Amira and Sami. ("Enter 77")
Sayid Jarrah and Kate took Ms. Klugh hostage outside The Flame when Mikhail Bakunin held Locke at gunpoint. ("Enter 77")
Locke took both Ben and Alex hostage, while Kate and Sayid were held prisoner by the Others. ("The Man from Tallahassee")
Sayid and Kate were captured by the Others when they attempted to rescue Jack from the Barracks ("Left Behind")
Anthony Cooper was held prisoner by the Others. ("The Man from Tallahassee") ("The Brig")
Anthony Cooper was held prisoner in the Black Rock by Locke. ("The Brig")
Jack captured Ben after believing he had killed Sayid, Jin and Bernard. ("Through the Looking Glass")
Ryan Pryce, Tom and Jason took Jin, Bernard, and Sayid hostage at the beach camp. ("Through the Looking Glass")

Jack allowed Ben Linus to go into Locke's custody. ("The Beginning of the End")
Locke's group detained Charlotte Lewis. ("Confirmed Dead") She was then traded for Miles by Sayid. ("The Economist")
Locke held Miles and Benjamin Linus prisoner. ("Eggtown")
Kate was held without bail pending the outcome of her trial. ("Eggtown")
Sayid and Desmond were detained in the Kahana's sick bay. ("The Constant")
Michael was imprisoned for destroying the engines on the Kahana. ("Cabin Fever")
Richard Alpert and the Others took Kate and Sayid hostage ("There's No Place Like Home, Part 1")

Hurley was arrested and held at the L.A. County Jail. ("The Lie") ("The Little Prince")
Daniel, Miles, and Charlotte were taken captive by the Hostiles in 1954. ("Jughead")
The DHARMA Initiative imprisoned Sayid. ("Namaste")

Charlie was arrested at Los Angeles International Airport. ("LA X, Part 1")
Jack, Kate, Hurley, Sawyer, Miles and Sayid were captured by the temple guardians. ("LA X, Parts 1 & 2")
Richard was knocked unconscious and taken into the jungle by the Man in Black, who tried to convince Richard to join him. ("LA X, Part 2")
The Man in Black was trapped in Locke's body. ("The Substitute")
Ben was fitted with a crude leg iron & chain. ("Dr. Linus")
Desmond as locked in a room on Widmore's submarine. ("Recon") ("Happily Ever After")
The Man in Black was imprisoned on the Island itself. ("Ab Aeterno")
Richard was imprisoned in a jail and then on the Black Rock (in chains). ("Ab Aeterno")
The darkness / evil was imprisoned by the Island (cork metaphor). ("Ab Aeterno")
Desmond, Sayid and Kate were imprisoned in the L.A. county jail before escaping via Anna Lucia and Hurley. ("What They Died For")
Desmond was imprisoned in a well when pushed in by Locke to save him as a backup plan in case he could not kill all of the candidates. ("Everybody Loves Hugo")

Some may never be free of their pasts.

Kate ran from the Monster and hid in a thicket of bamboo, reminiscent of prison bars--she was a prisoner of her own fear here, until she used Jack's method of counting. ("Pilot, Part 1")
Locke was confined to a wheelchair before the crash. ("Walkabout")
Jin was stuck working for Mr. Paik. ("...In Translation")
Desmond ran off, so the castaways had to resume pressing the button. ("Orientation")
The occupants of The Swan were forced to push the button, to prevent a disaster ("Orientation").
Locke told Claire that babies, unlike adults, like the feeling of being constricted, but that only as adults, do we strive for freedom. ("Abandoned")
Hugo escaped from Santa Rosa Mental Health Institute. ("Dave")
Locke was a prisoner of The Swan, fearing what would happen if he no longer pressed the button. He was free of his imprisonment when he traveled to The Pearl and changed his view on The Swan. ("?")
First Radzinsky and Kelvin, then Kelvin and Desmond were confined within the Swan station by duty and fear. ("Live Together, Die Alone, Part 1")
In their final episode Nikki and Paulo were paralyzed by poison and buried alive. ("Exposé")

Alvar Hanso was held by Thomas Mittelwerk, who had taken actions in the name of Hanso and The Hanso Foundation. See the Norway video.
William T. Kilpatrick was kidnapped in a Dodge Sprinter van.