Comedian Eddie Izzard spent more than £36,000 campaigning for Remain in the EU referendum, according to official figures.
The Electoral Commission has released the first details covering more than £4.5 million of spending by 48 individuals, campaigners and groups in the run-up to the June 23 vote.
The biggest single declaration was for £676,016 by Darren Grimes - a fashion student who ran the social media-driven BeLeave campaign, with the backing of the official Vote Leave campaign.
On the Remain side, the biggest spenders were the We Are Europe group - described as a "collective of friends, artists, campaigners, creatives and doers" - who spent £326,445 trying to mobilise support among young people.
Other declarations ranged between £10,000 and £250,000, with Remain campaigners spending £2,917,667 to £1,901,815 by Leave.
Other prominent spenders on the Remain side included the DDB UK advertising agency with £249,715, the telecoms company Lebara Ltd with £220,573, as well as a number of trade unions led by Unite with £140,173, Usdaw with £104,190 and the TUC with £97,909.
On the Leave side, the Grassroots Out umbrella group declared £219,215, Global Britain Ltd £209,302, Rupert Murdoch's News Group Newspapers £96,898, brewers JD Wetherspoon £94,586, Economists for Brexit £54,000, and the RMT union £45,083.
Bob Posner, the Electoral Commission's director of political finance, said: "The information we have published today provides a first chance to see the amounts of spending by many of the campaigners at the referendum.
"The publication of this data is vital in ensuring transparency and accountability, both in how campaigners obtained funds as well as how they spent them."