The first follower you're likely to find in Fallout: New Vegas is ED-E, a happy-beeping bundle of mechanical joy who used to be one of the Enclave's eyebots but, with some repairs, can become the Courier's constant and vigilant companion instead. But what if ED-E was actually… ED-UARDO?
This mod by Diegonom gives your faithful robot companion a makeover, adding a jaunty sombrero complete with feather and a headband full of bullets. He'll also get a different mustache based on whether you choose to have ED-UARDO upgraded by the Followers of the Apocalypse, which improves his weapon, or by the Brotherhood of Steel, which improves his armor.
Now, I know what you're thinking. "What about the duplicate model eyebot you find during the Lonesome Road add-on?" Don't worry, the ED-UARDO mod generously gives the ED-E clone a sombrero too.
To install ED-UARDO you'll need to download it from NexusMods, and I recommend grabbing the optional combat music replacer from the files page as well so you can hear Los Tucanes de Tijuana play La Chona or Mariachi Vargas de Tecalitlán perform El Son de la Negra while you gun down raiders and Powder Gangers in the Mojave Desert.