There were at least nine suicides in the veteran community in October and November, as well as two in August.
Four of those happened in Townsville, home to Australia's largest military base.
Three of those who died cannot be named for privacy reasons. The other eight are: Craig Earl, ex-member of 5 RAR (NT); Cody Langham, 7 CSSB (Queensland); Braiden Russell, 3RAR (Queensland); Robert Phillips, RAAF Airfield Defence Guard (Queensland); Shane Holt, 8/9 RAR (Queensland); Josh Neumann who served with 4 Regt (Queensland); Leo Leppens, Military Police (Queensland) and Jules Gencarelli, ex-Navy.
It has led Tasmanian senator and veterans advocate Jacqui Lambie to say that veteran suicides should be treated as "one of Australia's most pressing problems".
Veterans organisations are struggling to understand why there has been a spike, and whether it's going to get worse.
A message posted on social media paid tribute to Private Braiden Russell, who died by suicide at Lavarack Barracks in Townsville on October 30.(Supplied: The Pineapple Express)
"We're all very very concerned," said Townsville-based veterans advocate Chris Mills.
"It's an epidemic.
"We don't know why and we don't know what to do about it."
A Defence spokesperson told the ABC that three full-time serving members "are suspected to have died by suicide" since August this year. But that figure does not include ex-service members.
"There is often no single cause or event that leads someone to take their own life," the Defence spokesperson said.
"Defence is committed to ensuring serving and ex-serving ADF members have access to the right support, at the right time, especially those who are vulnerable or at risk."
A tribute shared on social media for Private Shane Holt, who died by suicide on November 16, leaving behind a partner and 3-year-old son.(Supplied: The Pineapple Express)
A popular social media group run for and by veterans and serving ADF members, The Pineapple Express, has been cataloguing the suicide deaths in recent weeks and sharing tribute posts with the permission of affected families.
The group is pressing its members to keep in contact with friends who may have become socially distant.
"It’s great to see that the community is clearly becoming more aware and passionate about [mental health and suicide]; it demonstrates the start of a cultural overhaul," the group posted.
"Whether you are serving or ex-serving, know that we are a community that helps each other out."
But veterans' groups are concerned that they are filling that void while the Department of Defence should be taking more action to stem suicides in the ranks.