Eugene Francis is the (former) secondary antagonist of Boss Baby.
He is Francis's Big Brother and Right hand man. His job to ensure no one interflers Francis diabolical plan to achieve market dominantion.
Eugene is initially thought to be dimwitted as compared to his younger brother who orders him around. However, he is shown to be quite clever and tough as his brother as he helped pull out a trap on Tim Templeton and the Boss Baby and disguised himself as a babysitter to fool the Templetons into putting the two boys under his care.
Eugene was a member of the Francis family when they decided to adopt the infant Francis. However, Francis grew bitter towards Baby Corp for his dismissal and vowed revenge. Growing up, Francis founded Puppy Co. as a rival to Baby Corp and gave Eugene a job serving as his main lackey, becoming very popular to the public. Despite taking delight in aiding in his younger brother's schemes, Eugene finds it disapproving that he's being treated as a lackey as opposed to being a brother by Francis, as the latter would often order him around and sometimes uses him as a chair.
Eugene first appeared when Tim Templeton and the Boss Baby broke into the Puppy Co. offices to search for a file containing plans of a "Forever Puppy". However, they soon learn it was a trick, as Eugene (posing as an actor wearing a puppy suit) traps them into Francis' office, where Francis steals a secret formula from the Boss Baby, revealing his true plan to use the formula to create the "Forever Puppies" and sell them to become more popular than babies and put and end to Baby Corp.
With the secret formula at hand, Francis decides to head over to Las Vegas to oversee his operations and take Tim's parents along under the guise of a business trip. To ensure that Tim and the Boss Baby won't interfere, Francis gets Eugene to pose himself as a female babysitter named Eugenia to keep an eye on them in their house. However Tim and Boss Baby escape from Eugene with the help of Jimbo, Staci, and The Triplets. But as the duo finally board into a plane with Elvis impersonators, Eugene is revealed to have boarded with them, disguised as an Elvis impersonator himself.
Eugene then follows up the duo to the Puppy Co. convention, where he accidentally calls up to Francis, who (along with Tim's parents) spot Tim and the Boss Baby among the audience. Locking up Tim's parents in a giant heartbox, Francis orders Eugene to get rid of the kids, but they manage to outwit Eugene by going through play tubes to dispose of him into a kitten playbox.
Following the defeat of Francis (who's been turned back into a baby after falling into the secret formula pit), he attempted to attack both Tim and the Boss Baby for ruining his plans. However, he is stopped by Eugene, who redeems himself by putting a pacifier in Francis' mouth and puts him to sleep. Eugene then informs the duo that he will try to raise Francis properly as a baby without an evil heart and walks away with Francis in his hands.