As was widely expected, HTC announced its two halo devices for the first half of the year at Mobile World Congress today, the quad-core HTC One X and slim, dual-core HTC One S. First revealed as the HTC Edge and HTC Ville, respectively, the two handsets are both powered by Android 4.0 Ice Cream Sandwich and skinned with HTC Sense 4.0.

The One X, pictured up top (and better known by its final codename of Endeavor), features a Tegra 3 “4+1″ quad core processor, 4.7-inch, 720p HD display, and 1GB of RAM / 32GB ROM. It’s got a 1080p-capable eight-megapixel main camera with the new HTC ImageSense technology, along with a 1.3-megapixel front-facing webcam. Like the One S, and most high-end HTC devices of late, the X brings Beats Audio enhancements to music playback.

While the S (pictured above) shares many of the same specs as the X, it is highlighted by its 7.9-millimeter profile. The processor is a more traditional dual-core Snapdragon from Qualcomm, while the display is 4.3 inches at qHD resolution. RAM is the same 1GB as the One S, but built-in storage is only 16GB. The two phones share the same camera, as well as a Bluetooth 3.0 radio, Wi-Fi b/g/n, and the usual complement of sensors.

Look for these two flagships to begin rolling out globally in late March and early April, each with 25GB of free Dropdrop storage in tow. As of now, the One S has been tipped for US release on T-Mobile, with further carrier commitments to follow.

Update: The One X will also ship in certain markets as LTE-capable, utilizing a dual-core Snapdragon S4.

Update 2: HTC’s put up a support page for the T-Mobile One S, including a press shot.

Update 3: And the One X is coming to AT&T, although it will be the dual-core LTE version. Landing page here.