'Rob & Big' star Christopher 'Big Black' Boykin dead at age 45

Christopher "Big Black" Boykin has died at the age of 45.

The former star of MTV's hit reality show "Rob & Big" passed away on Tuesday morning and, though there's no official cause of death yet, people close to the late star have reason to believe that Boykin died of a heart attack, TMZ reported.

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Boykin, who served in the Navy before starring on the show, became famous by getting into mischief and hilariously random adventures with co-star Rob Dyrdek, for whom he served as a bodyguard. Their unlikely friendship was the subject of "Rob & Big" for three seasons that ran from 2006 through 2008. They also starred on "Fantasy Factory" together.

See photos of Christopher "Big Black" Boykin:

Dyrdek took to Twitter on Tuesday after news broke of Boykin's death to pay tribute to his friend in a series of heartfelt messages.

"My heart is broken. I don't want write this post. I don't want to believe that this is reality. I am so thankful for you," he tweeted alongside a photo of them from back in the day. "We truly were brothers that lived an unexpected unforgettable adventure. I just can't fathom that it would end so suddenly. [...] You will forever be in my heart."

"I am so thankful for this moment... thank you for being an amazing human being and brother," he tweeted with another photo of Boykin, playing with Dyrdek's child.

Christopher "Big Black" Boykin is survived by his 9-year-old daughter, Isis.

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