Shrinkler
An Amiga cruncher by Blueberry that squeezes executables with a context-modelling range coder — the 4k intro's favourite.
Written by Blueberry (Loonies) and aimed at the Amiga, though also used in cross-development. Unlike the older, faster packers, Shrinkler uses context modelling and range coding — in the spirit of LZMA — reaching very high compression ratios at the cost of slower decompression and more memory.
That trade-off is exactly right for size-coding, where a 4k or 64k production is measured in individual bytes and the unpack time never shows to the audience. Shrinkler took over much of the role PowerPacker played on the Amiga, much as Exomizer did on the C64.