Diethelm I of Toggenburg

Diethelm I of Toggenburg (c. 1150–1205/1207) is the earliest count of the dynasty whose line can be traced. He may have married Guta of Rapperswil, though she may instead have been the wife of the next Diethelm. If she was his wife, she brought the county of Uznach and the upper March around Grynau into the marriage.

Around 1200 the couple shared in the inheritance of several neighbouring lordships while pressed by St. Gallen Abbey and neighbouring lords. His sons Diethelm II and Friedrich I survived him, and the comital title is documented from 1209.