Rowling, 51, has 10.3 million followers on Twitter and regularly shares her views on politics and human rights, as well as her writing.
This week she caused a storm when she apologised to her legions of Harry Potter fans for killing off Severus Snape in the final book, released ten years ago.
Ms Trollope, 73, who has written 20 novels and is famed for her stories about country life and the intricacies of relationships, said: “Creating this mass following and tweeting several times a day is like wanting to be Cheryl or Kim Kardashian.
“Some writers like JK Rowling have this insatiable need and desire to be out there all the time, and that’s entirely driven by their ego.”
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Rowling’s Twitter spats include long-running battles with television host Piers Morgan, most recently over his refusal to condemn US president Donald’s Trump’s “Muslim travel ban”, and a “freedom of speech” battle with SNP MSP Pete Wishart after he criticised a journalist’s tweet.
Kevin Williamson, writer and founder of publisher Rebel Inc, which helped launch the careers of Irvine Welsh and Alan Warner, said he welcomed people expressing their opinions on Twitter.
“Twitter is an addiction and people find it difficult to stop and writers are quite good at compressing everything down. I think JK Rowling enjoys Twitter and having spats with people and vocalising her opinions.
“I’m not really sure what her motivation is, but I more have more of a problem with people who won’t discuss their views and are bigots underneath it all.”
Marc Lambert, chief executive officer of the Scottish Book Trust, praised Rowling’s use of Twitter.
He said: “JK Rowling has gone beyond being an ‘author’ and campaigns on many good issues. Also, publishers’ budgets are shrinking so writers being on Twitter is a natural evolution.”