Ewloe Castle is a native Welsh castle built by the Kingdom of Gwynedd near the town of Ewloe in Flintshire, Wales. The castle, which was one of the last fortifications to be built by the native Princes of Wales, was abandoned at the beginning of the invasion of Wales by Edward I in 1277. Its construction, using locally quarried sandstone, appears to have continued piecemeal over many years and may have not been completed. On taking the castle, the English Crown gave it little military value and allowed it to fall into ruin.

Ewloe is a village and electoral ward in the community of Hawarden in Flintshire, Wales. It is situated close to the Flintshire/Cheshire sector of the Wales-England border. The A55 expressway passes through Ewloe and its most notable landmark is Ewloe Castle. The Ewloe electoral ward had a population at the 2011 Census of 5,420. The urban area of the village is contiguous with Hawarden, Buckley and Shotton. The Office for National Statistics deems Ewloe to form part of the Buckley built-up area, which covers much of Deeside.