This obituary is part of a series about people who have died in the coronavirus pandemic. Read about others here.

The month of March began with a glorious Sunday morning, perfect for the St. Pat’s For All Parade in Queens that celebrates diversity and equality as much as Irish heritage and culture. Among the organizers was the gregarious Tarlach MacNiallais, who had worked long and hard for inclusion of the long excluded.

He was known for his decades of advocacy for L.G.B.T. and disability rights. “A battering ram on issues of importance,” according to Harriet Golden, a vice president at A.H.R.C. New York City, an organization that serves people with intellectual and developmental disabilities, where Mr. MacNiallais worked for nearly 35 years.

Mr. MacNiallais died on April 1. He was 57. The cause was complications of the coronavirus, according to friends and family.