Hayden Panettiere's BF Brian Hickerson's Instagram Disappears After Her Death

Hayden Panettiere's boyfriend Brian Hickerson completely vanished from Instagram in the wake of her death ... and it's unclear who pulled the plug.

Brian's profile was still active when Hayden's death was first reported Sunday ... but it has since disappeared. Anyone trying to visit the account is now met with an error message.

It's unclear whether Brian scrubbed or deleted the account himself -- or if Instagram removed it.

Brian's IG account previously boasted 2.8K followers.

Hayden was found dead Sunday in a South Carolina apartment complex after flying down there with Brian. Her cause and manner of death have not been determined.

TMZ broke the news ... Hayden and Brian had quietly rekindled their romance, but kept it under wraps to protect her career. Sources told us Hayden's camp viewed their complicated history as "bad for business" while she promoted her recent memoir.

Hayden and Brian started dating in 2018, and he held their relationship in high regard ... previously telling us Hayden "is the sweetest thing in the world."

Their relationship also came with serious legal turmoil ... Brian pleaded no contest in 2021 to two felony counts stemming from multiple alleged violent incidents involving Hayden.

Brian was sentenced in 2021 to 45 days in jail -- of which he served 33 -- along with four years of probation, mandatory domestic violence classes, and a five-year restraining order.

We asked Brian in May if Hayden was better off without him ... and he said he would be an "idiot" not to walk away and let her "flourish in her career." He called her the most talented person he'd ever met ... admitting they "probably wouldn't be good together."

You can catch Brian's full conversation with TMZ's Charlie Neff on YouTube.