That's right: From June 3 to July 2, there'll be a post each day highlighting Teenage Mutant Ninja Turtles canon immigrants. Now, because TMNT canon is a little confusing, it can be hard to tell what counts as a canon immigrant and what doesn't. So for the purposes of this blog, a TMNT canon immigrant is anything (a) from the movies, cartoons, video games, toy lines, or tie-in comic series that later appeared in (b) TMNT volumes 1, 2, or 4 [because they're by the original creators] or TMNT volume 5 [because the original creators are involved, it's the new official continuity, and its goal is to use as much of the diverse TMNT lore as possible].
Hun was introduced in the 2003 series as the leader of a street gang called the Purple Dragons. He first appeared in the third episode, "Attack of the Mousers" (February 2003). He became Shredder's right-hand man and stuck around for the entire series, eventually turning the Purple Dragons from a lowly gang into an organized crime syndicate that rivalled the Foot. He was also the primary antagonist for Casey Jones, in part because Hun burned down the store of Arnold Jones, Casey's dad.
Hun grew to be one of Peter Laird's favorite characters, so in Tales of the TMNT #56 (March 2009), Hun would be introduced with much the same backstory. Only this time, we would learn Hun's real name: Hunter Mason.
Real name in the Mirage continuity, I should say, because when he was introduced in the IDW series, his name was quite different: Arnold Jones! He first appears in Teenage Mutant Ninja Turtles #1 (August 2011)...
...but we don't find out he's Hun until Teenage Mutant Ninja Turtles Villains Micro-Series #6: Hun (September 2013). We also learn that in this continuity he created the Purple Dragons but walked away from it, until Shredder called on him at a low point and asked him to restart it and work for the Foot.