Warning: major spoilers ahead for the midseason premiere of Arrow.
The death of Laurel Lance in Arrow Season 4 has hung over everything that's happened in Season 5 to date. She was the second woman to wear the black mask of the Canary in Starling City, and she was the second to die a horrifying death. Laurel used her last words to secure a promise from Oliver that she wouldn't be the last Canary in Star City, and now Oliver has decided to make good on that promise, with the ideal candidate apparently even closer than he might think. The final scene of the midseason premiere revealed a woman who clearly has all the skills necessary to become the next Black Canary, and she's right over in Hub City.
We got our first look at the possible Black Canary 4.0 - that is, after Sara, Laurel, and Evelyn wore the mask - in a Hub City bar. Here, she proved that she is already a firm believer in Sara's philosophy that no woman should ever suffer at the hands of men by coming to the defense of an innocent woman and using a combination of brute force and her own version of a metahuman Canary Cry to take a couple of pushy drunkards out before they could go too far.
So who was she? Juliana Harkavy made her violent debut as Tina Boland, a former Central City detective who hates vigilantes. Given what we've already seen of her abilities and inclinations to fight for the rights of the innocent, we can bet that her hatred of vigilantes won't last the entire season. A new Black Canary is (presumably) on the way for Arrow, and she looks like she'll be different from all the others who came before.
Such fists of fury aren't particularly new for a female crime-fighter. We've had a Canary pummeling bad guys ever since Sara first entered the scene back in Season 2 as an expert ex-assassin. Laurel figured it out after a couple of boxing lessons in Season 3, and Evelyn did her best as the teenage Black Canary in Season 4. If Tina does become Black Canary 4.0 as it currently seems likely, she'll be the first with actual metahuman powers, and those powers could make her an invaluable ally to Oliver. Black Siren proved in the midseason finale that there are definite advantages to having a meta cry rather than needing to rely on technology to screech, so Tina could be a game-changer as Black Canary.
Of course, we can't say for sure at this point if Tina really will become the Black Canary for the long haul, since we only really saw her for a few moments at the end of the episode. Still, co-showrunner Wendy Mericle recently said that Tina will be a character very connected to DC Comics, and she revealed that Arrow's creative team would be troubled by writing a show about the Green Arrow without a Black Canary. All things considered, Tina is shaping up to become the next woman on Arrow to take on the mantle of the legendary comic heroine.
Personally, I was much more excited by the appearance of Talia al Ghul in the flashbacks than I was by the introduction of yet another Black Canary in the present. Season 1 proved that Arrow can work quite well without a Black Canary in the cast, and we've already sat through three Black Canarys who have used fisticuffs and a sonic pitch to subdue enemies. Team Arrow is already bloated with fighters as it is; did we really need Black Canary 4.0 on top of everybody else working as a vigilante in Star City? Yes, the hero is an important part of many Green Arrow comic stories, but Arrow has never followed comic canon exactly, and we've already had an overload already. Hopefully Arrow will find a way to do something refreshing with Tina as Black Canary 4.0.