"Time Thief", known in the OCG as "Chronodiver" (クロノダイバー Kuronodaibā), is an archetype of DARK Psychic/Machine monsters introduced in Savage Strike as a TCG Exclusive. They also have connections to the "Security Force" archetype, as seen in "Security Force Showdown".
The Psychic members are scientists with clothing to match, wearing uniforms and glasses befitting of their time travel theme. The Machine members primarily take on the appearance of robotic animals doubling as time travel gadgets, bar "Time Thief Bezel Ship" which as one can surmise is a ship.
Their main strategy is to spam the board with Level 4 monsters and attach different card types, including the opponent's cards, to their ace monster, the Rank 4 Xyz Monster "Time Thief Redoer". The Machine members tend to Tribute themselves to aid with this. To accomplish this, "Time Thief Winder" is able to add "Time Thief" cards from the Deck to your hand, making it a valuable asset. This can be done by Normal Summoning it, or by Special Summonint it via detaching material from an Xyz Monster you control. Alternatively, you could use the effect of "Time Thief Regulator" to Tribute itself (while controlling no other monsters) to immediately Special Summon "Winder" and another "Time Thief" from the Deck. "Regulator" can also revive itself from the GY if an Xyz Monster you control is destroyed by battle, though be careful as it will banish itself when it leaves the field after doing so. "Time Thief Chronocorder" will do the same though it can Tribute itself during your opponent's Battle Phase to make them take battle damage that turn if they continue to attack. "Time Thief Bezel Ship" Tributes itself to attach cards from the opponent's GY to your "Time Thief" Xyz Monsters, but can also detach those materials to bring itself back to the field. Said Xyz Monsters are "Time Thief Perpetua" and "Redoer"; "Perpetua" can Special Summon "Time Thief" Monsters from your GY during your Standby Phases, as well as target another Xyz Monster of yours and attach 1 "Time Thief" card from your Deck to it. This makes her perfectly capable of supplying "Redoer" with the needed materials for his own effects, as he is able to detach up to 3 different kinds of materials from himself to activate the corresponding effects: detaching a monster banishes "Redoer" until the End Phase, a Spell will let you draw 1 card, and a Trap will place a face-up Card the opponent controls on the top of their Deck. Given this is a Quick Effect, this allows "Redoer" to become tricky to deal with on top of him being able to snatch cards from the top of your opponent's Deck each Standby Phase.
"Time Thief Startup" is a Quick-Play Spell that lets you immediately Summon a "Time Thief" monster from your hand, instantly triggering the effect of "Winder" or setting up "Regulator"; it is also able to banish itself from the GY to supply your "Time Thief" Xyz Monsters with all 3 materials needed for their effects, making it highly valuable. "Time Thief Hack" is a Continuous Spell that protects your Xyz Monsters from being destroyed or targeted by opposing effects the turn they are Summoned, on top of letting you boost your monster's ATK by 300 for each material it has, but also lets them attack directly if at least 1 of their materials belongs to the opponent. "Time Thief Flyback" is a Normal Trap that can be used to supply your "Time Thief" Xyz Monsters with material from the hand or Deck, and can banish itself after this to attack any card in your opponent's GY to your monsters as material. "Time Thief Retrograde" is a Counter Trap that can negate the activation of opposing Spells/Traps and, instead of destroying them, turns them into material for monsters, thus making it a powerful option against cards that would benefit from being in the GY.
The archetype has great synergy with the "Heraldic" archetype, which supports both Psychic and Machine Decks. As all members are of the DARK Attribute, they also benefit from generic DARK support as well as some Machine support like "Gear Gigant X". Generic Xyz Monster support can also work amazingly well with the Deck, such as "Overlay Regen" and "Xyz Reborn".