Lilioid monocots or lilioids is an informal name used for a grade of five monocot orders (Petrosaviales, Dioscoreales, Pandanales, Liliales and Asparagales) in which the majority of species have flowers with relatively large, coloured tepals, broadly similar to those of lilies. Another name for this group is petaloid monocots, because the flowers have tepals which all resemble petals. In older classification systems, still found in many books and other sources, many of the species in this group of plants were put into a very broadly defined family Liliaceae (lily family).

The diagram shows a cladogram of the monocots in which the bracket marks the lilioid monocots, namely the orders Petrosaviales, Dioscoreales, Pandanales, Liliales and Asparagales. The lilioid monocots all have flowers which can be considered to have been derived from a lily-like flower with six relatively similar tepals, six stamens, and a superior ovary composed of three carpels, with nectaries at the base. This pattern is primitive (plesiomorphic) for the lilioid monocots. Various trends are apparent among the lilioids, e.g. a change to an inferior ovary and a reduction of the number of stamens to three. In some groups (e.g. the genus Trillium in the Liliales), the tepals are clearly differentiated, so that the flower has three coloured petals and three smaller green sepals. Almost all lilioid monocots retain at least three petal-like tepals.