Dr. Elliot Katz, a fierce animal rights activist and veterinarian who helped shape the modern movement with his advocacy group In Defense of Animals, has died at 86.

Katz died at his home in Corte Madera in Marin County on March 24 after a year of declining health related to two surgeries, according to his daughter, Danielle Katz.

A fervent love of animals and unwavering moral compass won Katz both admirers, including the well-known chimpanzee expert Dr. Jane Goodall, and critics, ruffling fur and feathers along the way.

The New York native filed numerous lawsuits and was arrested 37 times for civil disobedience during his decades of activism. One of the first to practice nonviolent organized resistance on behalf of animals, Katz saw it as “a powerful tool to speak up for animals,” according to his daughter, who followed in his footsteps and now works for PETA.

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