13. Lord Sugar, Tycoon
The entrepreneur and Apprentice star is well known for being outspoken, and nowhere is this more apparent than on Twitter, where there's no mediating layer between his brain and his audience. Normally this takes the form of spats with the likes of Chris Evans ("Ginger") and Piers Morgan ("dimwit"), but the High Court did force him to remove a tweet referencing the trial of Lord Taylor of Warwick after he'd overstepped the line. Knows how to milk the medium: his live Twitter book-signing at the end of last year took the top trending spot for a full 24 hours.
Tweets as: @lord_sugar Peer Index: 87 Authority: 88 Activity: 42 Audience: 96 Follows: 68 Followers: 1,641,388Follow @Lord_Sugar