Whence Tyrannus tyrannus?

Scientific names are sometimes of obscure origin, and I’m wondering about the genus name of a family of birds known as flycatchers. They’re called tyrants, but I can’t really figure out why (unless they were named by a group of flying insects once.) Does anyone know the derivation of this term? Thanks, Dopers. (Colibri?) **

The scientific name is that of the Eastern Kingbird. Both the common and scientific name refers to the fact that these birds are extremely aggressive in defending their territories, and will chase even much bigger birds away. As the link says:

Added to this is the fact that the bird has a bright red crown patch. The crown patch is usually concealed but erected in display like here.

Other members of the genus are equally aggressive. It gives its name to the entire family of Tyrant Flycatchers, the Tyrannidae. Not all of them (or even most) are so aggressive, it’s just that Tyrannus is the type genus for the family.

[Aside]
Tyrannus dominicensis(*), the grey kingbird or locally, Pitirre, is often romanticized in Puerto Rico as a symbol of the spunky little guy standing up to the big guys. But in reality it’s a mean little ill-tempered tough who will pick a fight with anything he thinks is violating his personal no-flight-zone, including the wholly innocuous.

(*Why do I get the feeling no Dominican ornithologist wrote a single line about this bird during the rule of Rafael Trujillo?)
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