4=. Ricky Gervais, Actor and comedian

You don't have to be a signed-up member of the Twitterati to have felt the fall-out from Gervais's activity in the medium. A spate of tweets last year using phrases such as "Good monging everyone", "Night night monglets" and "Two mongs don't make a right" provoked a furious response from disability campaigners and others who saw nothing funny about using a word that appeared to mock people with Down's syndrome. Gervais's defence was robust (if not entirely convincing): "Well done everyone who pointed out that Mong USED to be a derogatory term for DS [Down's Syndrome], Gay USED to mean happy. Words change. Get over it." Nearly two million followers (or "twonks", as he calls them) appear to have done so.

Tweets as: @rickygervais PeerIndex: 91 Authority: 92 Activity: 41 Audience: 97 Follows: 36 Followers: 1,924,542