William Douglas Cullen, Baron Cullen of Whitekirk, is a former senior member of the Scottish judiciary. He formerly served as Lord Justice General and Lord President of the Court of Session, and was an additional Lord of Appeal in the House of Lords prior to the transfer of its judicial functions to the Supreme Court.

The Lord President of the Court of Session and Lord Justice General is the most senior judge in Scotland, the head of the judiciary, and the presiding judge of the College of Justice, the Court of Session, and the High Court of Justiciary. The Lord President holds the title of Lord Justice General of Scotland and the head of the High Court of Justiciary ex officio, as the two offices were combined in 1836. The Lord President has authority over any court established under Scots law, except for the Supreme Court of the United Kingdom and the Court of the Lord Lyon.