COLL (short for Corners of Last Layer) is a 3x3x3 last layer substep in the CxLL group that solves (orients and permutes) the last layer corners while preserving the last layer edge orientation, leaving only edge permutation (EPLL). It is principally used as a last layer for ZZ (as it has a higher skip chance and is nicer for OH than OCLL/PLL when used with EPLL) or an add-on to Fridrich, when the last layer edges are already oriented after F2L. COLL has 42 cases including mirrors (24 without). 2 of these are the adjacent and diagonal corner permutation.
COLL is not to be confused with CLL, also short for "Corners of Last Layer." The difference is that CLL preserves the F2L but not the last layer edges orientation, so it leaves the LL edges scrambled and the next step would be full ELL. For some cases the CLL and the COLL are the same algorithm, but for other cases the CLL is much shorter. For CLL and COLL algorithms, see the page on CxLL Algorithms.
One possible extension of COLL is ZBLL. This LL method solves the entire LL if the edges are already oriented, but it has 493 cases. Another one is OLLCP which solves the corner permutation and orients the last layer with a total of 331 algorithms for all last layer cases.