Cops are looking for the stocky crackpot who assaulted at least four people in Manhattan early Wednesday — including three victims who were slashed with a boxcutter.

The bushwhacking binge began at around 1:20 a.m. when the assailant got on a northbound No. 4 train at the Broadway-Lafayette station, punched a man and grazed him in the face with a boxcutter, according to police.

The thug and victim got off a stop later at the Union Square station, where the crazed man slapped a 20-year-old woman in the face, cops said.

The madman’s angry spree continued above ground, when he walked to a store in Union Square and asked a homeless man for a couple of dollars. The man refused and was slashed with a boxcutter.

“The [attacker] just popped out, out of nowhere. [The victim] doesn’t know what [he was attacked] with, but he thinks it was a blade,” said a store owner who spoke to the homeless victim.

Moments later, along East 14th Street, the thug confronted a man waiting for a bus. The slasher asked the man for a dollar, and when the man refused, the suspect cut him, too, police said.

Cops released a picture and a video of the attacker, who is described as about 5 feet 8 and 250 pounds.