Patrick McDonell officially replaces Kevin Vickers in the House.
The former police officer also served as Canada's ambassador to Ireland.
He was lauded as a hero for helping to end the 2014 attack on Parliament Hill.
The former House of Commons sergeant-at-arms was hailed as a hero after the 2014 Parliament Hill attack.
And he already has one potential supporter in caucus.
Don't mess with this family.
"Mr. Vickers responded instinctively."
"I certainly wasn't going to be offering any resistance to anybody there. I was basically outnumbered 200 to one."
Canada's ambassador to Ireland, ladies and gentlemen.
"I could die running or I could die buying my partners some time."