William Arthur Roger Mullin (born 12 March 1948) is a former Scottish National Party (SNP) politician.

[3] He is an Honorary Professor at the University of Stirling,[4] and lectured postgraduates on Applied Decision Theory, The Political Environment, and Organisation Change.

He was the SNP candidate at the Paisley North by-election in 1990, where he finished in second place behind Irene Adams of the Labour Party, with 29.4% of the vote.

[13] As a Member of Parliament, Mullin was a Treasury Spokesperson for the SNP, and a member of the Regulatory Reform Select Committee [14] He led a campaign in Westminster to reform Scottish Limited Partnerships which had been exposed by the Herald newspaper in Scotland [15] as being vehicles for tax evasion and laundering of criminal assets.

Since leaving Parliament, he has continued to comment [16] and campaign on Scottish Limited Partnerships, including being critical of the Law Society of Scotland's lack of effective action.

[23] After leaving the House of Commons, Mullin was appointed Special Envoy for the All Party Parliamentary Group on Explosive Threats in July 2017.