Sonic & Knuckles Sprite Sheets – Sega Genesis - Sonic Galaxy.net

Mighty and Tiara custom Sonic sprites

Sonic Mania/Unused Graphics - The Cutting Room Floor

Custom / Edited - Sonic the Hedgehog Customs - Sonic (Sonic Mania, T-Posed) - The Models Resource

PC / Computer - Sonic Mania - Dr. Robotnik / Eggman - The Spriters Resource

Custom / Edited - Sonic the Hedgehog Customs - Classic Capsule (Sonic Mania-Style) - The Spriters Resource

Sonic Mania - Special Stages, Bonus Stages, & Time Attack Shown Off, Page 16

PC / Computer - Sonic Mania - Death Egg Robot - The Spriters Resource

PC / Computer - Sonic Mania - Shiver Saw - The Spriters Resource

Sonic in Undertale Spritesheet by Ninjacat025 on DeviantArt

The VG Resource - Dolphman's submissions