The crooked knife sometimes referred to as a "curved knife", "carving knife," or "mocotaugan," from the Cree term "môhkotâkan," is a woodworking knife, typically with a curved end. The crooked knife is a common tool found amongst the native Americans of the Eastern Woodlands as well as non-native woodworkers. The crooked in "crooked knife" refers to its unusual shape with the handle set at an oblique angle to the blade. The blade can be straight or curved, long or short and can be made of a steel forged specifically for the knife, or from reused hardened steel from another source. The shape of the blade, whether curved or straight, is a function of the carving purpose of the user: straight for whittling wood, making splints for baskets and incising, curved for hollowing out bowls and masks and ladles, as well as myriad other usages.

The 1971 documentary César et son canot d'écorce (César's Bark Canoe) illustrates the use of a crooked knife in the construction of a birch-bark canoe.