Saga Most widespread species in Star Wars - Humans, Duros, Twi'lek?

In other words, which species are present on the widest number of planets?

I would guess that Duros are up there at the top with Humans, as the only other species except humans known to have given rise to a prominent offshoot species, the Neimodians. They are also known for being hyperspace pioneers, explorers and widespread spacers, like Humans. But beyond that, we should try to go on how commonly they turn up in streets of Coruscant, Taris or Nar Shadda in TV and video games like Knights of the Old Republic, The Clone Wars, and Jedi Knight: Dark Forces II. I would rank them:

The Most Prolific Spacers:


Humans


Duros

1). Humans (near-Human offshoots: Twi'leks, Zabraks, Mirialans, Zeltrons, Rattataki, Arkanians, Chiss, etc)

2). Duros (near-Duros offshoots: Neimodians, etc)

Both Humans and Duros are prolific spacers, were early hyperspace pioneers, and founding members of the Galactic Republic, living on prominent Core Worlds. Both species also gave rise to offshoots, some even dating to before written history, when primitive generation ships and sleeper ships colonized the galaxy.

Species Spread by Slavery:


Near-Human Twi'leks


Droids

3). Twi'leks

4). Droids

Twi'leks seem as widespread as Duros and Humans too, but unlike Humans and Duros, they were transported as slaves from their barren homeworld of Ryloth to various other worlds, by the Hutts and other species in ancient times, before becoming emancipated and successful members of galactic society. I also include Droids here, and they may outnumber many sentient species, since Droid is not a single species but a class of intelligent machine, built by almost every species in their image.

Immigrant Species:


Gran


Near-Human Zabrak


Bith


Ithorians


Quarren


Chadra-fan

5). Gran

6). Zabraks

7). Bith

8). Rodians

9). Devaronians

10). Ithorians

11). Quarrens

12). Chadra-fan

13). Ugnaut

14). Snivvians

15). Aqualish

16). Ancona

After the big three species, Humans, Duros and Twi'leks, it seems that Gran are the most widespread, having famous colonies like Malastare, and being present everywhere, such as thugs on Nar Shadda or shop owners on Coruscant. You can always see a Gran on the streets of any planet. Perhaps Bith after that? After those species, Rodians, Devaronians, Ithorians and Quarrens maybe? I'm probably missing an obvious one. The small Ugnauts and Chadra-fan are two of my favorites.

Mercenary Species:


Nikto


Weequay

17). Nikto

18). Weequay

19). Klatooinians

20). Gammorians

21). Trandoshans

22). Rattataki

These species also show up a lot, and are often seen traveling in mercenary and pirate bands, as clients or armies of the Hutts, etc, due to their homeworld being inside Hutt space, or having unique talents for hunting. One species that I wish was re-introduced is the Rattataki, the original species of Asajj Ventress, before she was changed to another. They are near-Humans and came from a war ravaged post-apocalyptic world, and just look cool.

The Opposite - Extremely Isolated Species:


Skakoan


Geonosian

A). - Skakoans

B). - Geonosians

C). - Muuns

D). - Mon Calamari

E). - Selkath

F). - Sii-ruuk

G). - Kaminoans

These species are still populous, but are instead largely confined to a single planet, for cultural, historical, logistical, or biological reasons. Leading the Techno Union, the powerful Skakoans have a Core World ecumenopolis like Coruscant, Denon, Alsakan, Empress Teta, etc, but they rarely venture off planet, due to their atmospheric needs and xenophobia. Geonosians, being an insectoid hive species, have a huge population without any ecumenopolis, but they are confined to Geonosis by their hive behavior, except during those times work details were sent off world for the Confedracy during the Clone Wars. Muuns are largely confined to their homeworld Scipio, and biggest colony Muunilinst. Mon Calamari, Selkath, etc, are likewise rarely leave their homeworld.

 

I like this topic, and I've always liked to picture sectors where humans are "background aliens" compared to one dominant species. I guess there's no way to empirically rank this stuff, and the ST kind of does a number on the former seemingly common species, so it's all up to each viewer's "vibe". I would have humans and Twi'leks at the top and Rodians close the top since they were prevalent in the PT and TCW and eventually snuck back into Disney onscreen stuff. Points for species who've had more than one or two named speaking characters onscreen too. Duros don't strike me as especially more common than some of your "immigrant" category choices, but I'm going off of onscreen only stuff mostly and no old EU stuff at all. Good call on the Grans via the multiple homeworld thing, I'd say. Aqualish vault to a pretty high position just based on overuse of a single TCW/Rebels background model (and Ithoirans and Bith do well by a similar standard).

There are a few I'd move out of the "mercenary" category because while you're right that that's mostly where you see them, there are notable Jedi and other non-sleazy examples of a few of them.