What do you call a transformer separated from a wall plug?
Those are modular supplies. The connector where the figure 8 plugs in can take a direct plug, that has us or euro or whatever mains connector. By coincidence they also use the IEC 60320-1 C7 and C8 Figure eight connector.

This is done because it is cheaper to make one universal 120/240 power supply, and a bunch of physical adapters, which can then be paired as needed. Smart/cheap manufacturing.

One particularly well known oem who uses these type of adapters is Apple, for both laptop, tablets, and I believe iPhone as well. So a oem iPad charger will work like this.