OVAs were a big part of why the Anime industry is different from Western Animation.

The technical definition of OVAs do exist in Western Animation as well.  OVA stands for Original Video Animation, it refers to Animations that were directly released to home video.

However straight to video releases in Western Animation are usually feature length, with 70 Minutes being the standard for the line of Direct to Video DC Animated movies that started in 2007 but 90 minutes for the 2008 Dragonlance: Dragons of Autumn Twilight movie. 

The Anime OVA industry that started in the 80s and reached its height in the 90s had some OVAs of comparable runtime to those, like Lupin III The Fuma Conspiracy. But the standard was getting something basically the length of an episode of a TV show or maybe just a little bit longer, maybe a full 30s minutes like TV episodes pretend to be but really aren’t due to commercials. 

And that’s what I think the western mindset has trouble relating to, paying the full price for a VHS tape or DVD and only getting one single episode feels unthinkable to us.  Remember Video Rentals never became a thing in Japan, no one was renting these before deciding if they were worth it, and largely because of that the standard price to buy a VHS was a lot more expensive in Japan than it was in the US even factoring in the Yen v Dollar exchange rate. So these Otaku were willingly paying a lot of money for just 30 minutes of content.

English localized releases of OVAs when they happened at all usually came later when they could put multiple episodes of a series on one tape or disc. So even Americans who got into Anime through bargain bin English Dubs of 90s OVAs never experienced what following OVAs was like in Japan.

I at first thought the one thing that could be a true Western OVA was Pryde of The X-Men, but then I learned that was a TV special first.

So when recommending an Anime from that era to someone not versed in how the Anime Industry works, they may ask if it’s a Movie or a TV show even though many really are neither but something harder to explain the concept of. 

Today the OVA is basically dead.  They still exist only for Hentai and the occasional bonus episode of a TV series included with its BluRay Release which fits the technical definition but isn’t being distributed the same way. However when they died is difficult to pin point, they lasted longer than I initially thought. 

One could argue they ceased to be the same as what they originally were as soon as DVDs replaced VHS as the standard format of Home Video releases.  I wonder if that is something that took longer in Japan then it did in the US or happened sooner?  The youngest movies I ever watched in a VHS format were from 2002 (Spider-Man and Attack of The Clones) but I'm pretty sure Return of The King had VHS releases in 2004 however I recall by 2005 at least all my local Video Rental places only had DVDs. 

But while their golden age was past plenty of original OVA releases happened in the 00s like Studio BeeTrain's Murder Princess.

I had in a few Blog Posts proclaimed Tenchi Muyo: War on Geminar from 2009-2010 the last OVA series. But I kinda knew that was not quite true even at the time.  Code Geass Akito of The Exiled and Gundam The Origin were OVA projects of the 2010s I was well aware of, and while they are part of established franchises they really cannot be dismissed as mere bonus episodes.  

However they are series where every episode has about a 70 Minute Run Time. So in that sense they are OVAs technically but not quite the same as the Classic OVAs I’ve been talking about. The Gundam Unicorn OVAs are close to that but a little shorter.  The War on Geminar Episodes were 45 minutes per episode, also a little longer than what the average originally was but not feature length. 

The last of the Detective Conan OVAs came out in 2012.  While all of those OVAs fit the “bonus episode of a TV show” description in terms of their content, the way they were released does seem to have been like classic OVAs.  Then there's the Rei and Kira OVAs from the Higurashi franchise (and Outbreak which I don't recommend).

Today the role OVAs used to play is now filled by ONAs, but many ONAs are also functionally the same as a TV Anime in how they come out, plus the full season binge releases.