A display apparatus, comprising: a display panel to display an image; and a window member disposed on the display panel, wherein the window member comprises: a plurality of flexible base films stacked upon one another, each flexible base film being substantially transparent, and wherein at least one of the flexible base films comprises at least one of polyimide, poly(methyl methacrylate), and tri-acetyl-cellulose; and a protective film disposed on the plurality of flexible base films, the protective film being substantially transparent, wherein each of the flexible base films comprises a plurality of protrusions and grooves formed between the protrusions, wherein each flexible base film comprises a base portion from which the protrusions extend, the base portion having a first thickness H1 between a bottom surface of the base film and a bottom surface of the grooves, and each of the protrusions having a height H2 between the bottom surface of the grooves and an upper portion of the protrusion, wherein the protrusions have a width W1 between lateral side edges of the protrusions, wherein the grooves between adjacent protrusions have a width W2 between lateral side edges of the grooves, and the ratio H1:H2:W1:W2 of the thickness of the base portion H1 to the height of the protrusions H2 to the width of each protrusion W1 to the width of each groove W2 is 1.00: 0.25~0.50: 1.00~5.00: 0.50~1.50, and wherein H1 is greater than or equal to 50 micrometers. a display panel to display an image; and a window member disposed on the display panel, wherein the window member comprises: a plurality of flexible base films stacked upon one another, each flexible base film being substantially transparent, and wherein at least one of the flexible base films comprises at least one of polyimide, poly(methyl methacrylate), and tri-acetyl-cellulose; and a protective film disposed on the plurality of flexible base films, the protective film being substantially transparent, wherein each of the flexible base films comprises a plurality of protrusions and grooves formed between the protrusions, wherein each flexible base film comprises a base portion from which the protrusions extend, the base portion having a first thickness H1 between a bottom surface of the base film and a bottom surface of the grooves, and each of the protrusions having a height H2 between the bottom surface of the grooves and an upper portion of the protrusion, wherein the protrusions have a width W1 between lateral side edges of the protrusions, wherein the grooves between adjacent protrusions have a width W2 between lateral side edges of the grooves, and the ratio H1:H2:W1:W2 of the thickness of the base portion H1 to the height of the protrusions H2 to the width of each protrusion W1 to the width of each groove W2 is 1.00: 0.25~0.50: 1.00~5.00: 0.50~1.50, and wherein H1 is greater than or equal to 50 micrometers. a plurality of flexible base films stacked upon one another, each flexible base film being substantially transparent, and wherein at least one of the flexible base films comprises at least one of polyimide, poly(methyl methacrylate), and tri-acetyl-cellulose; and a protective film disposed on the plurality of flexible base films, the protective film being substantially transparent, wherein each of the flexible base films comprises a plurality of protrusions and grooves formed between the protrusions, wherein each flexible base film comprises a base portion from which the protrusions extend, the base portion having a first thickness H1 between a bottom surface of the base film and a bottom surface of the grooves, and each of the protrusions having a height H2 between the bottom surface of the grooves and an upper portion of the protrusion, wherein the protrusions have a width W1 between lateral side edges of the protrusions, wherein the grooves between adjacent protrusions have a width W2 between lateral side edges of the grooves, and the ratio H1:H2:W1:W2 of the thickness of the base portion H1 to the height of the protrusions H2 to the width of each protrusion W1 to the width of each groove W2 is 1.00: 0.25~0.50: 1.00~5.00: 0.50~1.50, and wherein H1 is greater than or equal to 50 micrometers.