We'll be updating this article whenever we hear more about the handset's release date, price and specifications, so be sure to keep it bookmarked.
Release dateHTC has all-but-confirmed that the One M9 will make its debut at this year, having summoned press to an event in Barcelona on 1 March (below).
There's no word yet when the handset will arrive on shelves.
PriceThe price of the HTC One M9 has yet to make its way onto the online rumoursphere, but it's likely to carry a similar price tag to its predecessor. If so, it will cost around £500 SIM-free.
SpecsThe HTC One M9 isn't expected to arrive for another couple of months, but that hasn't stopped the handset's specifications leaking in full.
The next-gen HTC One, codenamed 'Hima', is expected to retain the metal body of the HTC One M8, but is likely to be slightly chunkier at 144.3x69.4x9.56mm. There's no word on how much the handset will weigh.
This specs leak comes via Upleaks, and suggests that the HTC One M9 will pack a 64-bit Qualcomm Snapdragon 810 processor under the hood, also confirming that it will arrive running Google's Android 5.0 Lollipop software.
This, typically, is expected to come with HTC's custom user interface on top, and the firm is expected to debut HTC Sense 7.0 alongside the smartphone.
Since then, however, reports out of China claim that HTC will opt for a 64-bit octa-core MediaTek chip. This will apparently arrive paired with 3GB RAM, and will equip the handset with support for Cat 6 LTE speeds.
Despite many of its rivals launching with QHD screens, the HTC One M9 will reportedly have a 5in full HD 1080p display, hinting that it won't see an upgrade in the screen department.
A separate rumour via BGR's unnamed sources has debunked this, however, claiming that the smartphone will feature a 2560x1440 QHD display.
The handset is likely to see an upgrade in the camera department, as the leaked specs point to a 20.7MP rear-facing shooter. It's unclear what front-facing camera the One M9 will feature, but speculation suggests a sensor between 4MP and 13MP.
We can expect to see a 2,840mAh battery, a slight upgrade from the 2,600mAh offering on the One M8, along with 32GB internal storage expandable up to 128GB via microSD.
We might not be seeing just one HTC One M9 model, either. According to a tweet from Evleaks (below), HTC's next-generation flagship smartphone could launch in two versions - the second with a larger screen and a physical home button.
The HTC One M9 is expected to launch with upgraded accessories too, including a new DotView case.