One of the closest substitutes for curry powder is turmeric. This yellow gem is a key ingredient in many curry powder blends and has a similar warm, earthy flavor. You can use it as a 1:1 substitute in most recipes, and it's also a great addition to scrambled eggs, soups, and roasted vegetables.
Another great option is garam masala, which is a blend of ground spices that adds a deep, complex flavor to dishes. While it's not an exact substitute, it pairs well with other spices like cumin, coriander, and cinnamon to create a similar flavor profile. Think of it as the ultimate team player that enhances the flavors around it.