Fill-in can refer to: * A puzzle, see

Fill-In (puzzle) Fill-Ins, also known as Fill-It-Ins or Word Fill-Ins, are a variation of the common crossword puzzle in which words, rather than clues, are given, and the solver must work out where to place them.

* In numerical analysis, the entries of a matrix which change from zero to a non-zero value in the execution of an algorithm; see Sparse matrix#Reducing fill-in * An issue of a comic book produced by a different creative team than the one regularly assigned to the series, published either to avoid missing a deadline or to give one or more of the series's regular creators a break

See also