Courtney Ford is cutting the cord on her marriage ... filing for divorce from her actor husband famous for playing Clark Kent.
The "Dexter" star beelined it to court Wednesday and filed to divorce "Superman Returns" star Brandon Routh after over 17 years of marriage.
In the docs, obtained by TMZ, Courtney is going with the boilerplate "irreconcilable differences" as the reason for the split ... and she does not give a date of separation.
Courtney and Brandon have one minor child together, 12-year-old son Leo ... and she's seeking joint legal and physical custody.
Courtney's seeking spousal support and she checked the box to terminate the court's ability to award Brandon spousal support.
The estranged Hollywood couple got hitched way back in 2007 at El Capitan Ranch in Santa Barbara ... they dated for three years before he popped the question in 2006, so they were together for well over 2 decades.