鸭洲（英语：Robinson Island，或音译作 Ap Chau），又名大鸭洲，是香港的一个岛屿，地区行政上属于北区。位于沙头角海以东，吉澳以西。

该岛屿非常细小，只有0.016平方公里，岛形狭长，阔度仅有100码。鸭洲是香港有人居住而面积最细的离岛，现时仅剩人口不足20人。鸭洲的名命是因为其形状确像一只半浮于水面的鸭。

鸭洲的主要岩石由水成岩（沉积岩的一种）组成，岛的东面石滩有无数彩色的石卵，可作收藏。因岛上全为嶙峋岩石，游人前往时应注意。在鸭洲亦可找到角砾岩（沉积岩的一种）。

Ap Chau (Chinese: 鴨洲), meaning "duck island", also known as Robinson Island, with a size of 0.04 km² is an island in the Crooked Harbour, in the north-eastern New Territories of Hong Kong. It is located in Ap Chau Bay (鴨洲海) and is under the administration of North District. The island had 8 inhabitants as of June 2008. Islets located close by include Ap Chau Pak Tun Pai, Ap Chau Mei Pak Tun Pai, Ap Lo Chun, Ap Tan Pai and Kau Tau Shek.