His sister, Rebecca Pfaffinger, said in a social media post he was found dead in his car alongside his assistance dog last month.

She told celebrity news site TMZ he had fallen asleep in the vehicle in a car park in Arizona and had died of heatstroke. His dog, Hans, also died.

"It is with a heavy heart my family has suffered a loss way too early," she wrote on Facebook.

"Ben was a great son, brother and uncle. He was fun to be around and made us laugh quite often.

"Still, going through his things, I find myself laughing at little videos or notes of his, in between crying.

"My brother Ben was found in his car, along with his beloved service dog Hans, deceased on 13 June.

"We believe he went there the evening of the 12th to deposit some residuals.

"[Found in his car] and never got out of the car to do so. He fell asleep and died from vehicular heatstroke."

She told TMZ her brother suffered from depression, bipolar disorder and had a sleep disorder that often kept him awake for days.

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Gregory appeared in all four seasons of ALF, which saw a furry alien crash land his spaceship into the garage of the Tanner family, who decided he could stay with them.

He was nicknamed ALF - short for Alien Life Form.

Gregory played the character of Brian, the son of the Tanner family, for more than 100 episodes.

He also featured in several television shows including The A-Team and T. J. Hooker.