Crossbones and Sin (the Red Skull's daughter).
Crossbones is simply the head and vest from the single-carded Captain America: The First Avenger line Crossbones and the body of Retaliation Roadblock. I added a fodder belt that has a knife and holster, a fodder pistol, and a fodder gun which I think is from the World Peacekeepers line. I painted some details on the gun and freshened the brass bullets on the vest.
Sin is the Red Skull head from the Captain America movies with a dark wash, and the body from the ROC Scarlett with reactive armor. The machine pistol is from a Baroness.
Here is a size comparison of the most logical bodies from which a Crossbones can be made. L - R, they are the stock Hasbro MU Crossbones, my Crossbones based on Roadblock, (Captain America for size comparison purposes), a WIP Crossbones using Ares and Wrecker parts (with a placeholder head just for this picture), and the DC Multiverse Bane.