SPOILER ALERT: This article contains spoilers for "X-Men: Apocalypse," which is in theaters now.
MISTER SINISTER
The first big reveal, the Essex Corp name, is a major deal because "Essex" is the surname of one of the X-Men's most prominent villains: Mister Sinister. Essex Corp is most certainly a shout out to the character, a creepy, glam rock geneticist born in the Victorian era and obsessed with genetics, cloning and meddling with the building blocks of life for his own selfish purposes. The fact that this Essex Corp was concerned with snatching a vial of Wolverine's blood makes the reveal even more Sinister. Then there's the fact that Richard E. Grant has been cast in "Wolverine 3" as a "mad-scientist type" villain. It looks like "X-Men: Apocalypse" may have confirmed that that "mad-scientist type" is Mister Sinister.
X-23
What the Essex Corp men placed in the briefcase is another potentially massive reveal. They took a sample of Logan's blood to, presumably, take it to a villain known for creating clones (most notably of Jean Grey and his henchmen the Marauders). Wolverine does have a clone in the comics -- a very notable one, so it's possible that this post-credits scene sets up X-23, Wolverine's teenage female clone. The character debuted in the "X-Men: Evolution" cartoon before becoming a popular addition to the X-Men comics. She currently stars in "All-New Wolverine," where she's taken up the mantle of Wolverine. X-23 is already rumored to be making her debut in "Wolverine 3," and "X-Men: Apocalypse" director Bryan Singer has admitted that he pitched the idea of a female Wolverine to Fox.
Could Mister Sinister be the one to create X-23, and could both characters play a part in Hugh Jackman's final "Wolverine" film? Just going by the post-credits scene of "X-Men: Apocalypse," it sure does look likely.