You likely remember Vizago from Star Wars Rebels. He's a Devaronian with a broken horn who named his crime syndicate after said broken horn. But how exactly did his horn get broken? Believe it or not, this is a question with a certain answer, and I can tell you all about it!
We actually get to see Vizago's horn get broken in the Adventures in Wildspace series- the first Star Wars books I reviewed for the blog. In book 3, The Heist, Vizago gets in a fight with Shalla Mondatha (a bounty hunter hunting the children that are the main characters of the book), because the children (and by extension, Shalla) are trying to retrieve the head of their beloved and very valuable droid.
During this fight, Shalla actually shoots his horn off- and that's why he has the broken horn we see in Star Wars Rebels. While maybe not super special or exciting, it was an interesting detail in those books that I enjoyed. And I hope you're happy with your extra bit of Vizago knowledge!