Alastair Aiken (born 6 November 1993), better known by his online alias Ali-A (or by his original alias Matroix), is a British YouTuber known for Call of Duty and Fortnite commentaries and vlogs. His main channel Ali-A has a subscriber count of over 16 million, with its total views exceeding 4 billion. His second channel, More Ali-A, has a YouTube subscriber count of 5.1 million and a total of over 959 million video views. On 23 April 2018, Ali-A created a new channel, titled "Clare & Ali" with his partner, Clare Siobhan. The channel has since gained over 480,000 subscribers and generated more than 3.5 million video views.
Aiken often refers to his YouTube subscriber fanbase as the "Ali-A Army". In July 2015, he was awarded the Guinness World Records for 'Most Popular Call of Duty Channel by views' and 'Most Popular Call of Duty Channel by subscribers'. Aiken frequently attends the Electronic Entertainment Expo (E3) as well as other video game conventions. In 2013, Aiken wrote a guest blog post in Huffington Post UK. The Huffington Post has also stated that "Ali is one of the UK’s most popular and influential entities globally and is at the forefront of the online and YouTube revolution." In September 2015, Aiken, along with Tom Cassell and Daniel Middleton, starred in Legends of Gaming Live, with the trio being referred to as "[s]ome of the most popular YouTubers in the [United Kingdom]". Redbull's eSports division has referred to his main YouTube channel as the "biggest Call of Duty YouTube channel." In March 2016, Clickible.com listed Aiken as the seventeenth "Most Famous Youtuber [sic]... on Earth". Later that year, Business Insider listed him as the ninth most popular British YouTube star – the same ranking they gave him in 2015. On 6 June 2017, the BBC referred to Aiken as a "YouTube megastar".