Alvin Cheng Kam-mun (Chinese: 鄭錦滿, born 23 June 1988), also known as "Brother Four Eyes" (Chinese: 四眼哥哥), is a Hong Kong political activist, a member of Civic Passion, and founder of student activist organization Student Front.

On the 16th, the four-hour rally on a lawn outside the summit venue attracted participation by many overseas students from Hong Kong, Taiwan and Mainland China.

[11] On the morning of 27 April 2015, Cheng was involved in a dispute with supporters of Avery Ng, the vice-chairman of the League of Social Democrats, outside Mong Kok Police Station regarding the progress of the Umbrella Movement.

[12] On 20 August 2015, Cheng was convicted of obstructing bailiff officers from clearing occupied roads in Mong Kok on 26 November 2014, and sentenced to 21 days' detention.

[15] Five weeks ahead of the (subsequently postponed) 2020 Hong Kong Legislative Council Election, on 30 July 2020, as Cheng preparted to stand, the government stated that he was among a dozen pro-democracy candidates whose nominations were 'invalid', under an opaque process in which, nominally, civil servants – returning officers – assess whether, for instance, a candidate had objected to the enactment of the national security law, or was sincere in statements made disavowing separatism.