Episode I: The Phantom Menace
(Darth Maul loses both legs. After Qui-Gon Jinn dies at the hands of Darth Maul, Obi-Wan Kenobi continues the duel. Obi-Wan manages to turn the fight around, take Maul by surprise, and chops him in two near the waist.)
Episode II: Attack of the Clones
Zam Wesell loses her right arm. After the Clawdite shape-shifter Zam Wesell makes an attempt on Padmé Amidala’s life, Obi-Wan and Anakin Skywalker chase her through Coruscant. They locate her when she ducks into a bar, and Obi-Wan uses his lightsaber to remove her right forearm before she can shoot him.
(Acklay loses two legs. One of the creatures in the arena during the Battle of Geonosis was the formidable acklay. It tried to take down Obi-Wan, but he escaped its pincers by slicing off two of the acklay’s front legs with his lightsaber.)
Anakin loses his right arm. When Anakin recovers from being hit with Force lightning from Count Dooku, he leaps back into battle only to lose more than half of his right arm to Dooku’s blade.
Episode III: Revenge of the Sith
Count Dooku loses both hands. In one of many turning points for Anakin, he exacts revenge upon Count Dooku and uses his lightsaber to cut off both the Sith’s hands. (Dooku would also lose his head.)
General Grievous loses two hands. General Grievous is quite the force to be reckoned with given his multiple appendages. Still, Obi-Wan sliced off two of his robotic hands in battle.
Mace Windu loses his right hand. When Mace discovers that Palpatine is the Sith they’ve been looking for, he decides to handle things himself rather than going through appropriate channels. Anakin stops Mace from killing Palpatine by removing Mace’s right hand from the rest of his body.
Anakin loses his left arm and both his legs. We all know how Revenge of the Sith ends, and it isn’t pretty. Anakin comes to hate Obi-Wan, and they engage in a brutal battle on Mustafar. Obi-Wan cuts off Anakin’s left arm and both legs in one swipe.
Episode IV: A New Hope
C-3PO loses his left arm. The Jundland Wastes are not to be traveled lightly, as C-3PO learned. He loses an arm to a Tusken Raider while trying to find R2-D2.
Ponda Baba loses his right arm. When Doctor Evazan and Ponda Baba give Luke a rough time in the Mos Eisley cantina, Obi-Wan steps in to help. He helps by cutting off Ponda Baba’s right arm.
Episode V: The Empire Strikes Back
Wampa loses its right arm. Wampas are no match for the Force. Luke summons the Force to retrieve his lightsaber, cuts himself down, and debilitates the wampa by, you guessed it, removing its right arm.
C-3PO loses all his limbs. Threepio really does not have good luck. Or any luck. This time around he puts his nose where it doesn’t belong while on Bespin, and Ugnaughts remove his limbs and later completely disassemble him.
Luke loses his right hand. When Luke encounters Darth Vader in Cloud City, he is in no way prepared for the duel. Luke does manage to put up a fight, but Vader has no trouble chopping off Luke’s right hand.
Episode VI: Return of the Jedi
Vader loses his right hand. Again. The next time Luke stands off against Vader, he’s more prepared. He’s wiser and more skilled. Before it’s all over, he pulls a reverse and cuts off Vader’s right hand.
Episode VII: The Force Awakens
This is the first film in which nobody loses any limbs! However, if we count Alan Dean Foster's novelisation as canon (and rumour has it that this was also a deleted scene), then there is one instance.
Unkar Plutt loses an arm. Rey bumps into Unkar Plutt, the scrap dealer from whom she stole the Millennium Falcon back on Jakku. Plutt's tracked the Falcon to Takodana, and isn't too happy that his prized possession's been stolen from under his nose. Rey aims her newly-acquired blaster at Plutt, only for him to snatch it off her. Chewbacca steps in to protect Rey, when Plutt lashes out. Chewie does what Han once warned C-3P0 about: he rips Plutt's arm out of its socket.
Other (less canonical)
(Padawan Hardin lost half a leg. At the climax of the Seventh Battle of Ruusan, Sith Lord Githany severed Padawan Hardin's leg from the knee down with her lightwhip. (In Star Wars: Jedi vs. Sith (comics).))
Balog lost a finger. Jedi Master Qui-Gon Jinn sliced a finger off Balog before the treacherous Absolute could press a transmitter to end Tahl's life. (In Jedi Apprentice: the Death of Hope (novel).)
Zule Xiss lost her left arm. Dark Jedi Asajj Ventress applied cho mok against Zule Xiss, slicing off her left arm. (In Star Wars: Republic: the Battle of Jabiim (comics).)
Nom Anor lost a limb. Leia Organa Solo used this technique on Nom Anor at the end of Yuuzhan Vong War. (In The New Jedi Order: the Unifying Force (novel).)
UnuThul lost an arm. Luke Skywalker also severed UnuThul's arm during their duel aboard the Admiral Ackbar. (In Dark Nest: the Swarm War (novel).)
(Nelani Dinn lost his right leg. Jacen Solo performed cho mok when he chopped off Nelani Dinn's right leg at Darth Vectivus's lair near Bimmiel in 40 ABY, beginning his path towards his grandfather's footsteps. (In Legacies of the Force: Betrayal (novel).))
(Tresina Lobi lost both legs. Jedi Master Tresina Lobi received a cho mok strike from Dark Lady of the Sith Lumiya from her lightwhip, during their duel in Coruscant's Fellowship Plaza, having both of her legs severed at the knees. (In Legacies of the Force: Tempest (novel).))
Salle Serpa lost an arm. Salle Serpa would have his arm cut off by Zekk. (In Legacies of the Force: Inferno (novel).)
(The last surviving Sith Lord lost both legs. Cade Skywalker severed the legs of the last surviving Sith Lord during the Mission to Daluuj in order to interrogate him. (In Star Wars: Legacy 48: Extremes, Part 1 (comics).))