| Official Name: | Mardenis, Indiana |
| Pushpin Map: | Indiana#USA |
| Pushpin Label: | Mardenis |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Indiana |
| Subdivision Type2: | County |
| Subdivision Name2: | Huntington |
| Subdivision Type3: | Township |
| Subdivision Name3: | Union |
| Coordinates: | 40.9042°N -85.4136°W |
| Elevation Ft: | 748 |
| Postal Code Type: | ZIP code |
| Postal Code: | 46750 |
| Blank Name: | FIPS code |
| Blank Info: | 18-46728[1] |
| Blank1 Name: | GNIS feature ID |
| Blank1 Info: | 438601 |
Mardenis is an unincorporated community in Union Township, Huntington County, Indiana, US.
Mardenis was named for William Mardenis, a railroad agent.[2] A post office was established at Mardenis in 1884, and remained in operation until it was discontinued in the year 1904.[3]