Jim 'The Anvil' Neidhart reportedly suffered a seizure shortly before his death.

The WWE legend - who was part of the iconic Hard Foundation tag team with brother-in-law Bret 'The Hitman' Hart - passed away on Monday (13.08.18) at the age of 63, and it has now been revealed his wife Elizabeth Neidhart told emergency personnel he had collapsed after appearing to have had a seizure.

According to TMZ, Elizabeth said Jim was having trouble sleeping and got up to change the thermostat, but then ''turned weirdly as if he were about to dance.''

The investigation report which was obtained by the publication then states Elizabeth said ''he then fell towards the wall and ground,'' and slammed his head when he hit the floor.

His wife phoned 911 believing he was having a seizure since he ''suffers from seizures and takes medication for it.''

Elizabeth claims the last time Jim had a seizure was last December, and she also notes the doctors believed he may have also had Alzheimer's - a disease which affects the brain and causes memory loss and difficulties with thinking, problem-solving, and language.

WWE confirmed the news of Jim's passing on Monday afternoon with a touching tribute to the late wrestling star.

It read: ''WWE is saddened to learn that Jim ''The Anvil'' Neidhart passed away ... Neidhart last competed in WWE in 1997 but his legacy lives on today through his daughter, Natalya, who displays her father's signature charisma and toughness every time she steps in the ring.

''WWE extends its condolences to Neidhart's family, friends and fans.''

His brother-in-law Bret also took to Twitter, writing: ''Stunned and saddened. I just don't have the words right now.''

WWE Hall of Famer Ric Flair has also paid tribute, hailing Neidhart as a ''world class athlete and a man among men''.