The victim wasn't immediately identified but is believed to be 87-year-old Sing Ho.
Sources said firefighters entered an apartment at 285 Grand St., where Ho lived, and found the body on a bed.
The Medical Examiner will determine if the body found is that of the missing man.
The blaze broke out inside 283 Grand Street at around 10:15 p.m. Sunday night and quickly spread down the block.
Three residents, 29 firefighters, and 1 EMT were also injured in the blaze.
Heavy flames shot from the roofs of the six-story buildings into the night sky and firefighters made rescue after rescue.
Scores of residents were plucked off of fire escapes and helped down by firefighters.
An FDNY source tells Eyewitness News that the fire is not believed to be suspicious in origin, and likely started accidentally on the ground floor of a small "99 Cent".
The precise cause is still not known, and investigators have been unable to rule out a series of possible accidental causes because they have yet to gain access to the ruins of the buildings. Although it is not suspected, foul play has not been officially ruled-out.
The Red Cross says over 200 are left homeless after the blaze, and the cost of the fire could be up to $100,000.
Three tenants were seriously injured. Two elderly residents were in critical condition, while the third was serious.
They went to New York Downtown Hospital, Beth Israel Medical Center and the burn unit at Cornell Medical Center.
About 29 firefighters were injured. One was burned on the hands, the rest sustained minor injuries.
Residents of some 60 apartments were left homeless by the flames. The Red Cross is registering residents.
The flames appeared to break out in a first floor business and spread through the apartments on the above floors to the roof.
As the fire spread from building to building, fire officials escalated the blaze to a rare seventh alarm, with more than 250 firefighters and more than 60 Fire Department vehicles responding to the borough-wide call.