Watchman Island is a small sandstone island in the Waitemata Harbour of Auckland, New Zealand. It lies approximately 600 metres north of the Herne Bay suburb. In the mid-19th century, the island was known as Sentinel Rock, which appears under this name on an 1857 British Admiralty chart of the Waitemata Harbour.
The island is well visible from the Auckland Harbour Bridge, which caused it to briefly make headlines when Adidas in 2005 erected a metal crouching figure (shown doing a haka) as part of a campaign to promote the All Blacks during the Lions' rugby tour. While Adidas noted that it had consulted on the erection of the statue, it was eventually toppled from the top of the island by a saboteur claiming that it was culturally insensitive. The island is customary Māori property.