Slivers are creatures that share a hive mind, which allows them to share their abilities with other nearby slivers. The creature type was introduced in Tempest. The original Slivers were depicted with an armored vertebrate body, a long, bifurcated whip-like tail, one arm with a single talon for a hand, and a head with an armored crest. Variations on this appearance existed in accordance with the abilities each has to offer to the hive.  An evolved form had humanoid features.
The first slivers shown in the storyline lived in Rath. It's unknown from where they originally came. Volrath is said to have genetically modified them, but to what extent is also unknown. He attempted to create artificial slivers, but these were a poor approximation of the real thing and had no innate abilities to share with the hive.
Volrath used the hive to guard the Legacy and to attack Weatherlight and her crew on their quest to retake those artifacts and their captain, Sisay. Thanks to Hanna, who realized how the slivers' hive mind worked, the crew defeated them in the Furnace of Rath and Karn was able to convince the Sliver Queen to release the Legacy to him, arguing that the artifacts were as much a part of him as the slivers were a part of her.  
During the Rathi Overlay the slivers were transported to Urborg. Most of them were killed when they materialized in the heart of a volcano, and all the others were killed in the subsequent battles of the Invasion.
One hundred years later, wizards involved in the Riptide Project on Otaria discovered sliver fossils on their journeys and planned to bring them back to life in order to study them. The Riptide wizards did not know the importance of the Sliver Queen, however, and didn't recreate her. Without her, the slivers went rampant and overran the island housing the project. 
At the same time the Mirari was causing havoc all over Otaria. The magical waves it produced accelerated the slivers' growth, but it also lured them to the mainland since they confused its call with that of their deceased queen. Most of the slivers were therefore present at the battle at Averru and were killed in the magical explosion that created Karona. A small group of slivers survived, however, and fused into the ultimate manifestation of the hive mind, the Sliver Overlord.
After the apocalypse
Slivers that survived the apocalypse caused by Karona's destruction and a few breeds that were "timeshifted" into the present by the violent upheavals of the time stream belonged to the few creatures that were able to flourish on the dying plane of Dominaria. As other species fought for survival in a world almost completely drained of mana, the slivers continued to multiply and mutate into new forms. Some of these new breeds mimicked traits of other life forms in the multiverse; the vampiric sliver fed upon the life essence of its prey and was strengthened in return, much like the dreaded Sengir clan and their ilk. The gemhide sliver adopted an ability similar to that of the fabled Birds of Paradise, creating mana of any color whenever it wished. Basal slivers possessed the innate drive to sacrifice themselves to provide for their nestmates, similar to the way the master breeders of the Ebon Hand used Basal Thrulls for their dark rituals. Another new strain present during this time was the shadow sliver, trapped between two worlds when the nest within the bowels of Volrath's Stronghold was overlaid on Urborg. Presumably, this breed was a terror to the Rathi Tribes who were also caught in the overlay in their home, the City of Traitors. Without the leadership of their Queen, these sliver swarms raged across the plane, largely unstoppable when gathered in great enough numbers. The destruction caused by the slivers was not necessarily malevolent, the hive-minded creatures only sought a new queen, new leadership to guide their numbers.
For a time, the planeswalkers Freyalise and Lord Windgrace maintained some control over the slivers in their respective realms. Once the Weaver King discovered the simplicity of their hivemind, he quickly took control of them for his own purposes and used them to wage war on their former masters. Since his destruction, the slivers are presumably once again without leadership, though it's indicated that the slivers' hivemind is slowly becoming sentient and self-aware, negating further need for a Queen.
The Hivestone, a strange artifact discovered within the ruins of the Stronghold, was later found to have been used by the various evincars of Rath's past to control the seething sliver hive and its Queen. Upon its rediscovery however, the device became a curse to its wielder, bending its possessor's will to the will of the swarm.
Slivers are implied to survive well into the future of Dominaria, taking on even more new and bizarre abilities.
On the shores of the eastern Sea of Shandalar, an evolved race of Slivers build the "Skep", a great nest or hive. The Slivers had gleaming, gemlike eyes and "hair" more like the squirming tentacles of a jelly-fish or polypod. Many still had a bestial appearance, but a few could generously be considered humanoid. All were covered with chitinous plates that glistened and slid about like oiled pieces of machinery. The creatures use a chittered speech. 
The slivers on Shandalar are divided between the human sized "less brood", with tails and singular claws, and "primes", which are bi-pedal and humanoid, looking like sentient races of Shandalar. One sliver, the hivelord, rules over all slivers of the hive. The hivelord is around 20 times the size of a human. 
Sliver is a creature type found in the Tempest block, the Onslaught block, the Time Spiral block and Magic 2014 sets. Most Slivers have an ability that grants all Slivers the same ability. Exceptions to this rule include Metallic Sliver, Sliver Overlord, Sliver Queen and Venser's Sliver.
Slivers first appeared in Tempest.
- A common cycle of 1/1 Slivers with a mana cost of C (C being one colored mana). These are Talon Sliver, Winged Sliver, Clot Sliver, Heart Sliver, and Muscle Sliver. 
- An uncommon cycle of 2/2 Slivers with a mana cost of C. These are Armor Sliver, Mnemonic Sliver, Mindwhip Sliver, Barbed Sliver, and Horned Sliver. 
- Metallic Sliver is a common Artifact Creature - Sliver with a mana cost of . Unlike most other Slivers, it has no abilities itself but is capable of gaining abilities granted by other Slivers.
- Uncommon cycle of 2/2 Slivers with a mana cost of two, with one for each allied color pair. These are Crystalline Sliver, Hibernation Sliver, Acidic Sliver, Spined Sliver, and Victual Sliver. 
- Sliver Queen is an atypical Sliver for multiple reasons. It costs WUBRG, is 7/7, and it grants no abilities to Slivers, but it has an activated ability that produces 1/1 colorless Sliver creature tokens, which can gain the abilities granted by other Slivers.
- A common cycle of 1/1 Slivers — Plated Sliver, Mistform Sliver, Crypt Sliver, Hunter Sliver, and Quick Sliver.
- An uncommon cycle of 2/2 — Ward Sliver, Shifting Sliver, Spectral Sliver, Blade Sliver, and Root Sliver.
- The first rare cycle Slivers, all 3/3 — Essence Sliver, Synapse Sliver, Toxin Sliver, Magma Sliver, and Brood Sliver.
- Brood Sliver produces 1/1 colorless Sliver creature tokens.
Scourge had only Sliver Overlord, which was printed in homage of Sliver Queen, a very popular card in casual Magic. Sliver Overlord was meant to be a "Sliver King" of sorts, but that does not fit with Sliver biology, so it instead became an overlord.  Like Sliver Queen, it shares both its 7/7 size and WUBRG cost. Its activated abilities represent its ability to call and control other Slivers, which can be used with other type changing effects and abilities to take control of opponents' creatures.
Another three years later Time Spiral added 26 new Slivers, as well as reprinting Essence Sliver and Spined Sliver as "Timeshifted" cards. The set included two commons, one uncommon, and one rare of each color; one uncommon for each of the allied color combinations, and one artifact Sliver.
- The commons are Sidewinder Sliver, Watcher Sliver, Screeching Sliver, Shadow Sliver, Mindlash Sliver, Basal Sliver, Two-Headed Sliver, Bonesplitter Sliver, Gemhide Sliver, and Spinneret Sliver.
- The uncommon single-color Slivers are Quilled Sliver, Telekinetic Sliver, Vampiric Sliver, Fury Sliver, and Might Sliver.
- The uncommon two-color Slivers are Opaline Sliver, Dementia Sliver, Ghostflame Sliver, Firewake Sliver, and Harmonic Sliver.
- The rare Slivers are Pulmonic Sliver, Psionic Sliver, Plague Sliver, Sedge Sliver, and Fungus Sliver.
- The artifact Sliver is Venser's Sliver, a 3/3 for with no abilities.
- Also, the set added Hivestone, an artifact that makes all creatures you control Slivers.
- A common cycle: Battering Sliver, Poultice Sliver, Reflex Sliver, Sinew Sliver, Spitting Sliver, and Synchronous Sliver.
- A cycle of uncommon enemy-coloured slivers that paid homage to previous cards of their color; Dormant Sliver, Necrotic Sliver, Frenetic Sliver, Darkheart Sliver, Cautery Sliver.
Future Sight had one cycle, two extras and a card that referred to slivers:
- The cycle consisted of five common slivers; Frenzy Sliver, Homing Sliver, Lymph Sliver, Mesmeric Sliver, and Virulent Sliver.
- As a final tribute to the Queen, a new legendary WUBRG 7/7 sliver was printed: Sliver Legion, which pays homage to Coat of Arms.
- The Spellshaper Sliversmith produces 1/1 colorless Sliver artifact creature tokens named Metallic Sliver
- Vedalken Æthermage returns target Sliver to its owner's hand, when it enters the battlefield,
- Rare cycle: Bonescythe Sliver, Galerider Sliver, Syphon Sliver, Thorncaster Sliver, Megantic Sliver
- Three uncommons: Battle Sliver, Manaweft Sliver, Steelform Sliver
- Six commons: Blur Sliver, Groundshaker Sliver, Predatory Sliver, Sentinel Sliver, Sliver Construct, Striking Sliver
- Hive Stirrings produces 1/1 colorless Sliver creature tokens.
- Mythic rare sliver: Sliver Hivelord
- Uncommon cycle: Constricting Sliver, Diffusion Sliver, Belligerent Sliver, Leeching Sliver and Venom Sliver
- Sliver Hive produces 1/1 colorless Sliver creature tokens.
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- Mark Rosewater. (August 05, 2013.) "Twenty Things That Were Going To Kill Magic", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Doug Beyer. (May 6, 2013.) "Slivers Evolved", A Voice for Vorthos, Tumblr.
- Aaron Forsythe. (June 23, 2014.) "Magic 2015—It's In There", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Bruce Richard. (June 24, 2014.) "This Hive is No Mos Eisley", Daily MTG, magicthegathering.com, Wizards of the Coast.