The Rise of Skywalker features the notorious bounty hunter Dengar. J.J. Abrams really went out of his way to make sure hardcore Star Wars fans had Easter Eggs to hunt down. While the movie was just as divisive as the rest of the sequel trilogy, a lot of fans were satisfied with the way everything came to an end. The Skywalker Saga has officially come to a close with new movies tackling other characters in different timelines.
Dengar shows up in The Rise of Skywalker in the Kijimi scenes. He's located in the bar, but he looks a bit different than normal. The bounty hunter first appeared in The Empire Strikes Back and had a pretty big story arc in The Clone Wars too. While he's not exactly the sharpest tool in the shed, the character has managed to stay alive, albeit with some cyborg help. He looks a lot different than he did in his younger days as a result of aging and new cybernetic body parts that were added to aid slowing reflexes.
The Rise of Skywalker Visual Dictionary confirms that Dengar appears in the movie. In the dictionary, the character is named Rothgar Deng, which is an alias. One of the best-known bounty hunters in the galaxy would likely have to use an alias while getting around these days, so this makes sense. As for his new cybernetic "advancements," they were all done black market style, so they weren't done by professionals and probably explain why the character looks so tweaked in the movie. While Dengar was able to last this long, it appears that he may finally be dead now.
After the Kijimi scene, we know that the First Order puts the planet on lockdown as they search for Rey and the Resistance. After they escape, the First Order blows the planet to pieces, killing everybody who was not able to escape. Zorii Bliss and Babu Frik were able to get out safely, but the same can probably not be said for the slow moving Dengar. After all of this time and so many stories within the Star Wars universe, it appears that the bounty hunter's time is up, thanks to J.J. Abrams.
Dengar was a member of Krayt's Claw, which was a syndicate of bounty hunters including Boba Fett, Bossk, and Asajj Ventress. They were first put together to secure property valuable to Lord Otua Blank of the planet Quarzite. They all show up briefly in The Empire Strikes Back, except for Boba Fett, who has a larger part in the story do to capturing Han Solo. While Boba Fett got the glory, Dengar got to live a whole lot longer as a result of staying in the shadows. You can head over to Penguin Random House to purchase The Rise of Skywalker Visual Dictionary.