Bill Fagerbakke Legally Separated -- Wife Sponges Off Spongebob

The actor who voices the Spongebob's best friend, Patrick Star, is lookin' fresh these days, because his estranged wife just took him to the cleaners ... TMZ has learned.

Bill Fagerbakke and his wife, Catherine, just got legally separated. For some reason, without even getting divorced, they entered into a property settlement agreement ... obtained by TMZ.

Here's the lowdown:

-- Catherine gets 50% of all earnings, including what Bill made on "Coach" and "Spongebob" -- he averages around $700K a year.

-- Catherine gets the $2.4 million family house

-- Catherine gets $13,500 a month in spousal support

-- Catherine gets a 2010 Lexus hybrid SUV

-- Bill gets to keep his $3,000 security deposit on the home he's renting

-- Bill gets to keep his hoopty -- a 2011 Mini Cooper

But one bright light for Bill ... he gets to keep his cherry '54 Chevy.