DC Comics

DC Comics (short for Detective Comics Comics) is considered apart of the "big two" of Western Comic book publications, alongside Marvel Comics. While DC has yet to produce any Pony media themselves, their products have been mentioned several times.

Friendship is Magic cartoon

 * Shining Armor and own comics that parodied Action Comics #1
 * The fictional city of Maretropolis is probably a reference of Metropolis. In addition, the Power Ponies are a blend of The Justice League and The Avengers
 * Although the names of the heroes are based off various comics in general. Star Sapphire is most likely named after the Star Sapphires.

Friendship is Magic comic book

 * Spike advertised an attraction featuring Action Ponies and Adventure Comics, a possible reference to Action Comics and Adventure Comics.
 * Shining Armor had a poster for the Foal Titans, a parody of the Teen Titans.
 * Dragon Comics sold copies of Action Ponies
 * Princess Celestia owns the city of Kandor.
 * Princess Celestia also owns a book with a Green Lantern logo.
 * A multiversal event known as "Crisis of Infinite Equestrias" once transpired, a reference to "Crisis of Infinite Earths"
 * A Green Lantern pony appeared.

Other connections

 * Both Tara Strong and Scott Menville appeared in the Teen Titans cartoon as prominent voice actors, for Starfire and Robin respectively.
 * Frank Welker has appeared in many DC works, as well as Scooby-Doo works that crossed over with DC properties.
 * Gail Simone, writer for "Between Dark and Dawn", is arguably most famous for her work on DC's Wonder Woman comic series.
 * Nigela Ruka, the Albanian voice actress for Applejack provided the Albanian dub voice for Hawkgirl in Justice League.
 * Algiona Aga, one of the few Albanian voice actresses for Rarity provided the Albanian dub voice for Rarity in DC Super Hero Girls: Intergalactic Games