LeoPanthera

See also:

pbzip2: https://github.com/ruanhuabin/pbzip2

plzip: https://www.nongnu.org/lzip/plzip.html

And possibly the cleverest of the parallel compressors, tarlz, which, while still being backwards compatible with tar, also allows parallel decompression, something none of the others can do: https://www.nongnu.org/lzip/tarlz.html

ak217
Also https://github.com/vasi/pixz, which uses a more computationally efficient yet widely supported compression algorithm (lzma/xz) and adds indexing, making byte range access possible in large files within the archive (and does also support parallel decompression).