Orange-billed tern is a name applied to a group of three large terns in the genus Thalasseus with orange bills, which are quite similar in appearance and often considered difficult to identify, namely:
The greater crested tern (Thalasseus bergii) and the Cayenne tern (Thalasseus sandvicensis eurygnatha), which have yellow rather than orange bills, are sometimes also considered part of this group.