- Broderick- Most of the villains Booster fights are established as other heroes enemies. In volume one of the Booster Gold solo series Broderick was the guy with the most depth. A cop that was obsessed with bringing the lead to justice no matter what. The two leave on a truce and sadly the character was never seen again.
- Max Lord- Having Max go evil was poorly written, at least until Justice League Generation Lost wrote him as a conflicted man that valued his team. This was one of the most engaging conflicts Booster was involved in.
- Black Beetle- I'd rank him higher if Booster and him had more interactions or we knew more about him. Honestly I'd consider him more of a foil for Rip Hunter than Booster. Sometimes he fights Jaime Reyes too.
- Deathstroke- A Titan villain but I'd consider him a baddie for Dick. Now Slade is being written as a bad guy for Batman and DC at large.
- Blockbuster- The big baddie from the first Nightwing solo title.
- Lady Vic- I don't remember much about her but I've seen her around and I'm not following anything in current Nightwing books. I'm not counting the COO since their not one villain.
In general I think DC needs to focus on creating villains for characters. This is especially the case for the Robins.