The phrase "a key activist" is correct and usable in written English.
It can be used to refer to an important or influential person involved in advocacy or social change efforts.
Example: "She has been a key activist in the fight for environmental justice, organizing numerous campaigns and rallies."
Alternatives: "a prominent activist" or "a leading activist".
Last year the ACL expended 53 of its media releases on anti-LGBTI propaganda and was a key activist in the campaign against Safe Schools.
Ghalioun's statement came after a key activist group accused the leadership of marginalising council members and acting alone on major decisions.
"I do not have the right to demand that a Belgian produces energy my way but there is a real threat from these two reactors and I do have the right to protect my health," said Jorg Schellenberg, a key activist in the Aachen coalition for action against nuclear power.
We don't think the national guard is necessary," DeRay Mckesson, a key activist and organizer in Ferguson, told HuffPost Live's Marc Lamont Hill Tuesday.
Conservative Party Robinson was a founder member of Macclesfield Young Conservatives and rose through the ranks, becoming Cheshire Young Conservative Chairman (1982 84) and became a key activist in the moderate controlled North West Area organisation.
Former state Sen. Sheila Kuehl won the endorsement of a key activist group Saturday after a wide-ranging debate among five candidates vying to replace Los Angeles County Supervisor Zev Yaroslavsky.
Mr Baisalov is a former rights activist and was a key opposition activist over the past decade of Kyrgyz politics.
The gay community was eventually seriously affected by the AIDS epidemic, and Jones became a key AIDS activist.
J. Edgar Hoover heavily relied upon provocateurs in his infamous COINTELPRO program, used against the antiwar movement and its "key activist leaders," with Abbie and Jerry at the top of his list.
Young working-class Labour supporters who flocked to help Jeremy Corbyn win the leadership are being deliberately "priced out of democracy" by wealthy Blairites who have hiked the cost of a key conference, activists claim.
One of its key activists for a time was a convicted "Aryan" terrorist, and its leaders openly urged seceding from the United States and forming a country to be ruled by theocratic whites.
