ISO/IEC 7816-4 padding
A padding scheme that appends the byte 0x80 followed by zeros until the block is full.
It comes from the ISO/IEC 7816-4 smart card standard and is really bit padding in byte-sized form: a single one bit followed by zeros. The same method appears as padding method 2 in ISO/IEC 9797-1 for MAC computation. Padding is always added, even when the message already ends on a block boundary; in that case you get a whole extra block, because otherwise padding and data would be indistinguishable.
The advantage over PKCS#7 is that no length byte is needed. The receiver scans backwards for the first 0x80 and drops everything after it. The drawback is the one every deterministic padding shares in CBC mode: if the receiver reacts differently to broken and valid padding, you have a padding oracle. The scheme is innocent; the error handling decides.