In The Astounding Wolf-Man Gorgg is an ancient and evil golem that was imprisoned under Stonehenge. As soon as he is released by The Face he goes to kill the blood relatives of those who imprisoned him.
Lampshaded in the short-lived comic BMG, where the Big Bad releases The Dragon from a can labeled "Instant evil. Just add water."
In The DCU, the Phantom Zone is essentially an other-dimensional prison that holds numerous Kryptonian criminals. As such, there many stories where the prisoners escape and the heroes have to fight to throw them back into the Zone.
The Source Wall in The DCU is a huge cosmic barrier between the Source (the source of power behind existence itself) and the rest of creation. The Wall is decorated with the bodies and visages of all of the would be conquerors who have sought to claim the power of the Source for themselves, imprisoning them for all eternity. The Wall is one of the more effective Cans in fiction and only three people have ever escaped it. One of them, Yuga Khan (the father of Darkseid), managed to summon just enough power to free himself from the Wall...only to get himself imprisoned in it again in another bid to obtain the Source, this time for good. The second one was Darkseid himself, and he needed the help of the one who imprisoned him in the first place (Superman) to do it. The third was Superman, who was trapped by Darkseid and required the help of every variation of Supergirl from the last twenty years to break free.
Zom, from Doctor Strange - a surprisingly obscure hyperdemon who was sealed in a special amphora in another dimension. Horrifically powerful. He was initially imprisoned by a coalition of cosmic beings, including Eternity and frickin' Dormammu, and when he was let out, he frightened Umar (Dormammu's even scarier sister) so much she ran home and said she'd never come out again. Considering how bad-ass he is, the "can", or amphora, must truly be the can of the gods.
Fables' second Big Bad came out of his can due to the effects of the heroes saving the world.
Also, the djinn that Frau Totenkinder dealt with earlier, although that was more of a case of amoral and incredibly dangerous and destructive, especially in the hands of an evil man, but not evil in and of itself.
In Marvel comics, Galactus acts as a can on a greater, multiverse-destroying evil. Most of the energy he gets from his food goes to maintaining the seal, explaining his unusual diet.
In the Godzilla (2014) tie-in comic Godzilla Awakening, originally, Shinomura and Godzilla (and for that matter every radiovore) fled deep beneath the earth as the radiation levels receded. It was only after the bombing of Hiroshima that lured Shinomura from its hiding place.
Green Lantern: Rebirth revealed that the long-established "yellow impurity" in the Central Power Battery was actually Parallax, the "yellow fear entity," an insectile manifestation of that emotion, released when Hal "Greatest GL of them All" Jordan entered the Central Battery years before. Before it was in a box that was stolen from Maltus by Larfleeze and his crew. Later it was imprisoned in a Sciencell, and finally got ripped apart and stashed in four separate batteries.
The Warlock Graveyard in I Hunt Monsters is this, housing many powerful monsters in it and kept in check by an obelisk that needs to be recharged every century of so. It the protagonist's disbelief and reluctance that ends up freeing the monsters and he forced to track them down and re-seal them.
Justice League of America comics occasionally feature early JLA enemies the Demons Three (Abnegazar, Ghast, and Rath), evil beings who ruled the Earth a billion years ago until being imprisoned in crypts by mysterious powerful entities called the Timeless Ones. The three Demons were eventually summoned/released in the present by Felix Faust, with occasional other escapes from imprisonment since then.
The French comic book Les Légendaires introduces the Evil God Anathos, whose essence was trapped a long time ago by the other gods in a living prison called the Bearer. While his origin is a typical use of the trope, the way he comes back is partially subverted, as he frees himself by taking control of the Bearer and using Demonic Possession, as well as manipulating one of the protagonists rather than another villain; the original Big Bad, Darkhell, actually attempted to prevent his return rather than helping him.
Loki's first appearance shows him imprisoned inside a tree. He would become free only if his captivity causes someone to shed a tear. No one missed Loki strongly enough to want to cry, so he forces Heimdall to shed a tear by poking him in the eye with a leaf.
Another example of this in The Mighty Thor franchise is Mangog, the sum total of the hatred of a race that was slain by Odin. It was imprisoned with a warning on the door until released by the Rock Troll Ulik who thought it would be an ally against Asgard.
Then there were older foes of Asgard imprisoned by Odin. Ymir the Frost Giant, Surter the Fire Demon, and Skagg the Storm Giant, the last two were released by Loki to attack Odin.
And more recently, there's The Serpent, God of Fear and Odin's brother, who Odin sealed in a prison at the bottom of the ocean ages ago, until freed by Sin (who had been transformed into one of his Worthy).
Parodied in a 1983 nine-page story in Love and Rockets by Jamie Hernandez called Maggie vs Maniakk. Maggie plays with a "Mayamese mini transporter" and accidentally frees Maniakk, a costumed super evil trapped in limbo/the ninth dimension by Ultimax, a superhero now down on his luck.
In Lucifer, the seraph Meleos long ago created the Basanos, a living, extremely powerful living tarot deck as both a complement to Destiny's book (which contains nearly everything that will ever happen) and a means of recording and preserving humanity's thoughts. The latter function, however, corrupted the Basanos and turned them into beings of pure evil, so Meleos has since locked them in a box. However, when Lucifer demands the use of the Basanos for divination, Meleos resolves to destroy them and opens the box, whereupon the cards overpower him and escape.
Tiamut the Dreaming Celestial was exiled to Earth by his Celestial brethren for committing a crime against "life itself". Later revealed to be a case of Sealed Good in a Can. Tiamut objected when the others tried to cull the Deviants of Earth, and was punished for it. The Deviants understandably worship Tiamut as their savior.
A somewhat ambiguous example in My Little Pony: Friendship Is Magic (IDW), where Chrysalis and her Changelings are imprisoned in their own castle at the end of the first Story Arc with the animated Pinkie Pie suit to entertain them (well, entertain the soldiers, annoy Chrysalis). Twilight indicates it would take them "a while" to break out. However, recently, on page 11 of Friends Forever Issue #8, a sign under the Mount Monument observation deck reads "Sign the petition to add Queen Chrysalis to the monument" and bears Chrysalis' fresh signature, which in turn strongly suggests they have since recovered and are back to plotting and causing trouble for Equestria.
One episode of The Sandman had an Arabian Nights-flavored tale with a medieval caliph (kind of like a Muslim king/pope) who wanted to talk to Dream. The caliph went into a dark secret room and took out an ancient globe full of demons, threatening to break it and release them all. Morpheus appeared, took the globe and pocketed it, and then inquired what the caliph wanted.
Superman. Doomsday was living Sealed Evil, but ultimately broke out of his own can. He keeps getting re-sealed in stronger cans (we hope!).
The quote on the main page has Luthor being a bit resentful that somebody sealed Doomsday and dumped the can on Earth, but Earth did pretty much the same thing. Doomsday can only be temporarily killed, and even if you can do that you don't want him around when he wakes up again, because he mutates in such a way as to be immune to whatever killed him last time. So somebody managed it, packaged him up, and launched him into space, which eventually resulted in him landing on Earth. What does Cyborg Superman do with Doomsday's body? Strap it to an asteroid and throw it into space. It later turns out that Cyborg Superman is actually villain Hank Henshaw.
In the conclusion of The Thanos Imperative event, the now immortal Thanos is trapped in the Cancer Verse. Star-Lord and Nova trapped him there along with themselves to keep him from destroying their own universe in his rage at being forever denied the embrace of his beloved Death. Subverted when it turns out he escaped later on.
Jurid from Thieves & Kings, also known as "the Dawn Swallower", is a powerful monster, but spent a thousand years or so stuck in a glass bottle, trapped by a young girl.