Sonic the Hedgehog

Sonic the Hedgehog is a character from the Sonic the Hedgehog series. He appears as the main protagonist in (nearly) every different canon in the series.

Het

 * Sonade - the ship between Sonic and Shade the Echidna
 * Sonaisy - the ship between Sonic and Princess Daisy
 * Sonalina - the ship between Sonic and Rosalina
 * Sonally - the ship between Sonic and Sally Acorn
 * Sonamy - the ship between Sonic the Hedgehog and Amy Rose
 * Sonangle - the ship between Sonic and Tangle the Lemur
 * Sonaze - the ship between Sonic Blaze the Cat
 * Sonbul - the ship between Sonic and Bulma
 * Sonbunnie - the ship between Sonic and Bunnie Rabbot
 * SonDash - the ship between Sonic and Rainbow Dash
 * Sondonna - the ship between Sonic and Madonna
 * Soneach - the ship between Sonic and Princess Peach
 * Soneam - the ship between Sonic and Cream the Rabbit
 * Soneena - the ship between Sonic and Zeena
 * Soneezie - the ship between Sonic and Breezie the Hedgehog
 * Sonelise - the ship between Sonic and Princess Elise
 * Sonerci - the ship between Sonic and Perci
 * Soniara - the ship between Sonic and Tiara Boobowski
 * Sonicks - the ship between Sonic and Sticks the Badger
 * Sonicole - the ship between Sonic and Nicole the Holo-Lynx
 * Sonikal - the ship between Sonic and Tikal the Echidna
 * Sonilac - the ship between Sonic and Sash Lilac
 * Soniona - the ship between Sonic and Fiona Fox
 * Sonmaria - the ship between Sonic and Maria Robotnik
 * SonMerna - the ship between Sonic and Merna the Merhog
 * SonMiku - the ship between Sonic and Hatsune Miku
 * SonMina - the ship between Sonic and Mina Mongoose
 * Sonmo - the ship between Sonic and Cosmo
 * Sonouge - the ship between Sonic and Rouge the Bat
 * Sontena - the ship between Sonic and Palutena

Slash

 * Foxic - the ship between Sonic and Foxy the Pirate
 * MegaSonic - the ship between Sonic and Mega Man
 * Mephonic - the ship between Sonic and Mephiles the Dark
 * Metonic - the ship between Sonic and Metal Sonic
 * Sonadow - the ship between Sonic and Shadow the Hedgehog
 * Sonake - the ship between Sonic and Solid Snake
 * Soneggman - the ship between Sonic and Doctor Eggman
 * Sonespio - the ship between Sonic and Espio the Chameleon
 * SonExe - the ship between Sonic and Sonic.exe
 * Sonfinite - the ship between Sonic and Infinite
 * Sonilver - the ship between Sonic and Silver the Hedgehog
 * Sonis - the ship between Sonic and Chris Thorndyke
 * Sonjet - the ship between Sonic and Jet the Hawk
 * SonMario - the ship between Sonic and Mario
 * Sonoa - the ship between Sonic and Klonoa
 * Sonourge - the ship between Sonic and Scourge the Hedgehog
 * Sontails - the ship between Sonic and Miles "Tails" Prower
 * Sontoine - the ship between Sonic and Antoine D'Coolette
 * Sonuckles - the ship between Sonic and Knuckles the Echidna
 * Sonzor - the ship between Sonic and Zor

Polyships

 * Sonadaze - the ship between Sonic, Shadow the Hedgehog and Blaze the Cat
 * Sonadilver - the ship between Sonic, Shadow the Hedgehog and Silver the Hedgehog
 * SonSalAmy - the ship between Sonic, Sally Acorn and Amy Rose
 * SonShadAmy - the ship between Sonic, Shadow the Hedgehog and Amy Rose

Friendships

 * Team Sonic - the ship between Sonic, Miles "Tails" Prower and Knuckles the Echidna

Non-binary

 * SoNiGHTS - the ship between Sonic the Hedgehog and NiGHTS

Cargo Ships

 * SonChili - the ship between Sonic and a chili dog

Canon Relationships
Amy Rose

Sally Acorn

Fanon
As Sega's mascot and one of the key reasons for the company's success during the 16-bit era of video game consoles, Sonic is one of the most famous video game characters in the world. Also Sonic has been acknowledged as, undoubtedly, the most recognizable and famous character in the Sonic the Hedgehog franchise according to an official popularity poll.

In terms of shipping, as the main character of the series Sonic is the most shipped character in the Sonic fandom, and it's pretty popular to see him paired with Amy, Sally, Blaze, Shadow, or even with crossover characters.

Fandom
AO3