Panel filter elements having a pleat block and a seal member are described. The panel filter elements are arranged such that the seal members and pleat blocks can have curved and/or angled elements. The seal member of a filter element may be curved, angled, twisted, and/or has a varying cross-section. The inlet and outlet faces of the pleat block of the filter element may be curved and/or twisted instead of planar. In some arrangements, both the seal member of the filter element and the faces of the pleat blocks can be curved and/or twisted. The described filter elements may be may be flexible, such that the shape of the filter element and/or seal can conform to the shape of a filter housing, or rigid, such that the shape of the filter element remains substantially the same before and after installation into a filter housing.