For the US Alien Act of 1798, see Alien and Sedition Acts.

The Alien Act 1705 was a law passed by the English parliament as a response to the Scottish parliament's Act of Security of 1704, which in turn was a response to the English Act of Settlement 1701.

The Alien Act provided that Scottish estates held in England were to be treated as alien property, making inheritance much less certain. It also had an embargo on the import of Scottish products into England and English colonies - about half of Scotland's trade, covering sectors such as linen, cattle and coal.

The Act contained a provision that it would be suspended if the Scots entered into negotiations on the dispute between the two parliaments. Combined with English financial offers to refund Scottish losses on the Darién scheme, it achieved its aim, leading to the Act of Union 1707 uniting the two countries as Great Britain.