Ellis

Ellis is one of the four playable Survivors in Left 4 Dead 2. He's a goofy, beer-loving smart guy that likes to work with machines. According to Chet, he is "extremely excited" about everything, like managing to visit a concert and kill a lot of zombies, making him more of an optimist like Louis of Left 4 Dead.

Official Description
Most people would be scared witless by the zombie outbreak. Not Ellis—he's 21 and indestructible, so there was no way he was getting infected. The Savannah native respects his mother, loves his job and enjoys the simple pleasures in life. A little cocky, it remains to be seen if the end of the world will show him fear for the first time.

Relationships with other Survivors
As of now it is a bit unclear what Ellis' disposition towards the other survivors is.
 * Coach: Coach and Ellis don't have much of an evident relationship. Coach will be sad when Ellis dies, and vice versa. They do seem friendly when they talk to each other, however.
 * Nick: Nick and Ellis do not seem to have a very friendly relationship. Nick openly insults Ellis in many seperate occasions, and rarely compliments him. For that reason, Ellis doesn't seem to act very friendly towards Nick normally, but will say nice things about him, and seem genuinely sad when he dies.
 * Rochelle: Ellis has a fairly strong bond with Rochelle. Ellis is quite sad to see her go, and they joke around throughout the campaigns.

Quotes
"See: Ellis/Quotes"

Trivia

 * Ellis holds a handgun using only his right hand unlike the other Survivors who use both of their hands as seen in this video.
 * It appears that Ellis was the one who drove the car from the first campaign's finale to Dark Carnival's Highway.
 * In the Zombie Survival Guide trailer, Ellis is the only one that is attacked by Special Infected. A Jockey, Charger, Spitter, and a Smoker all try to attack him. This could imply that he is reckless and/or extremely unlucky. It could also be a reference to how Louis is often used as comic relief in many fan-made parodies out there.
 * Ellis was one of the only Survivors to have a skin, never featured in any game footage but screenshots. It can be seen in a picture above, featuring Ellis with a totally green cap, white shirt and jeans.
 * Ellis is the youngest character in Left 4 Dead 2, like Zoey in Left 4 Dead. Regardless, Rochelle's is 26, Nick is in his thirties, Coach is most likely around his mid or late forties, and Ellis is 21.
 * Ellis' "Bull Shifters" shirt can be unlocked via achievements for Xbox 360 avatars.
 * Ellis also seems to be unaware of appropriate times for conversation; he seems quite happy to speak of trivial things, which seems to irritate his fellow Survivors
 * Ellis appears to have the biggest amount of lines of all the Survivors ever made(1900 lines, 100 more lines than Coach and Nick have), making the aforementioned speculation most likely be confirmed.