To steal someone's thunder means to take credit for something that was actually done by somebody else.
1. It was obvious that it was due to team work that the rowers won the trophy, but Peter stole their thunder by snatching the Cup and hogging the limelight.
2. The senior manager stole his junior's thunder by claiming to be the sole person who brought the project to a successful end.
3. The ISC Lead Editor believed in giving credit where it is due and did not steal the thunder from the assistant editor.