Jeremy London -- Party of Foreclosure

That $20,000 he allegeldy owes American Express is nothin' -- because "Mallrats" and "Party of Five" star Jeremy London could also be losing his house!

According to documents filed last month in L.A. County Superior court, the TV-turned-direct-to-DVD star defaulted on his mortgage -- and unless he pays $12,856.81, Countrywide is looking to foreclose.

Countrywide says if he doesn't cough up the cash, the home will go up for auction October 21.