Juggernaut (Marvel Comics) Only had to touch the Gem of Cytorrak to initially receive his powers, not needed afterwards.
Various Lantern Corps (DC comics); each have rings that provide various themed abilities.
Alan Scott (DC Coics); via magical power ring and lantern.
Amazo (DC Comics); via copying Green Lantern's Power Ring.
Kratos (God of War); via various weapons and accessories (most notably the Blades of Chaos/Athena/Exile). It should be noted that Kratos is also granted innate, magical powers over the course of his storyline by various gods and other entities.
Shocker (Marvel Comics); via his gauntlets
Mysterio (Marvel Comics); via his tech and special effects
Dr. Octopus (Marvel Comics); via his tentacles
Green Goblin (Marvel Comics); via his tech.
Falcon (Marvel); flight via his wing harness
Captain America (Marvel); via the Super Soldier Serum
Black Cat (Spider-Man: The Animated Series); via Super Soldier Serum
Star Girl (DC Comics)
Star Man (DC Comics) (2nd)
Ben Tennyson (Ben 10); via the Omnitrix/Ultimatrix
Thor (Marvel); via Mjolnir.
Captain Marvel (Marvel); via Kree Nega-Bands
Rick Taylor (SplatterHouse); via the Terror Mask
All Power Rangers (Power Rangers); via their morphers
All Sentai Rangers (Super Sentai); via their henshin (transformation) devices
Rhino, Scorpion, Shocker, Dr. Octopus, Venom, Carnage, and Vulture (Spider-Man, Marvel); via their costumes
All Excorsists (D. Gray-man) via their Innocence)
Thanos, then Adam Warlock (Marvel); via the Infinity Gauntlet.
Dio Brando (JoJo's Bizarre Adventure); via the Stone Mask
Crimson Chin,Nega Chin, and Cleft (Fairly Odd Parents); via their "chins"
Shinnok (Mortal Kombat); via his amulet
Sonic characters (Sonic The Hedgehog); via the seven Chaos Emeralds
Mandarin (Marvel); via his 10 magical rings.
The members of Wetworks (Wetworks); via their symbiotic suits.
Noah/Grimoire (Soul Eater); via the Book of Eibon
Angry Video Game Nerd (Cinemassacre)
Linkara (Channel Awesome)
Jefferson (Once Upon a Time); via his magic hat
Mala Mala Jong (Xiaolin Showdown)
Samus Aaran (Metroid); via her Power Suit
Link (Legend of Zelda); via his Triforce of Courage
Zelda via her Triforce of Wisdom (Legend of Zelda)
Ganondorf Dragmire (Legend of Zelda); via his Triforce of Power
Sara Pezzini (WitchBlade); via her WitchBlade
Users of the Death Note (Death Note)
Vector Prime (Transformers); via his sword
Bearers of the Matrix of Leadership (Transformers)
Some heroes (Heroes); via the Red Formula.
Hiro Nakamura (Heroes); via the Kensei sword.
Vongola Guardians (Katekyo Hitman Reborn); via Vongola Rings
Will Vandom (W.I.T.C.H.); as keeper of the mystic Heart of Candracar
Rex Salazar (Generator Rex); the five Meta Nanites
Users of the Shen Gong Wu (Xiaolin Showdown series)
Most Modern-day Kamen Riders (Kamen Rider Franchise). The original Kamen Riders were mostly cyborgs, thus their devices were already a part of them.
Users of the shards of Shikon no Tama/Jewel of the Four Souls (InuYasha)
Kuwabara (Yu Yu Hakusho) originally needed to use a piece of a spiritually-powerful piece of wood to use his signature Spirit Sword.