From Destinypedia, the Destiny wiki
Some of the Lost Sector boss names seem to have been changed in Forsaken.
- EDZ, Earth
* Trostland * Terminus East - "Kalsis, Sunless Captain" is now just "Sunless Captain" * Outskirts * The Drain - "Drekthas, Metal Captain" is now just "Metal Captain" * Whispered Falls - "Keldrik, Drained Captain" is now just "Drained Captain" * Winding Cove - "Rannix, Drenched Captain" is now "Downpour Captain"
- Arcadian Valley, Nessus
* Exodus Black * The Rift - "Talas, Dusk Captain" is now "Tattered Dusk Captain" * The Cistern * The Conflux - "Primus Cal'aug" is now "Shayotet Partisan"
These are all the ones I've found.