An airfoil (60, 62, 200) for a gas turbine engine, the airfoil comprising: an airfoil body having a leading edge, a trailing edge, a first end, and a second end, wherein a direction from the first end to the second end is a radial direction and a direction from the leading edge to the trailing edge is an axial direction, wherein an airfoil-tip squealer pocket is formed in the second end of the airfoil body, wherein the first end is a root of the airfoil and the second end is a tip of the airfoil; a leading edge hybrid skin core cavity (134; 202) formed within the airfoil body and defining a cooling flow path extending from the first end to the second end of the airfoil proximate the leading edge of the airfoil, the leading edge hybrid skin core cavity having a first wall and a second wall, the first wall being a cavity wall that is part of an external wall of the leading edge of the airfoil body and the second wall is an internal wall or surface of the airfoil body that is not part of an external wall of the airfoil body; wherein the leading edge hybrid skin core cavity has a variable height-to-width ratio in a direction from the first end to the second end, with a first aspect ratio proximate the first end that transitions smoothly or gradually into a second aspect ratio proximate the second end, wherein the first aspect ratio is a low aspect ratio and the second aspect ratio is a high aspect ratio, and wherein leading edge hybrid skin core cavity transitions from a first geometry at the first end to a second geometry at the second end; and wherein the height is defined as a maximum distance between the first wall and the second wall and the width is defined as an arc length of the second wall; wherein the leading edge hybrid skin core cavity opens from an interior of the airfoil body at the second end such that, in use, cooling air is discharged from the leading edge hybrid skin core cavity into a recessed portion of the airfoil-tip squealer pocket. an airfoil body having a leading edge, a trailing edge, a first end, and a second end, wherein a direction from the first end to the second end is a radial direction and a direction from the leading edge to the trailing edge is an axial direction, wherein an airfoil-tip squealer pocket is formed in the second end of the airfoil body, wherein the first end is a root of the airfoil and the second end is a tip of the airfoil; a leading edge hybrid skin core cavity (134; 202) formed within the airfoil body and defining a cooling flow path extending from the first end to the second end of the airfoil proximate the leading edge of the airfoil, the leading edge hybrid skin core cavity having a first wall and a second wall, the first wall being a cavity wall that is part of an external wall of the leading edge of the airfoil body and the second wall is an internal wall or surface of the airfoil body that is not part of an external wall of the airfoil body; wherein the leading edge hybrid skin core cavity has a variable height-to-width ratio in a direction from the first end to the second end, with a first aspect ratio proximate the first end that transitions smoothly or gradually into a second aspect ratio proximate the second end, wherein the first aspect ratio is a low aspect ratio and the second aspect ratio is a high aspect ratio, and wherein leading edge hybrid skin core cavity transitions from a first geometry at the first end to a second geometry at the second end; and wherein the height is defined as a maximum distance between the first wall and the second wall and the width is defined as an arc length of the second wall; wherein the leading edge hybrid skin core cavity opens from an interior of the airfoil body at the second end such that, in use, cooling air is discharged from the leading edge hybrid skin core cavity into a recessed portion of the airfoil-tip squealer pocket.