Bandit is Angela Martin's cat.
After Dwight mercy-killed Angela's cat, Sprinkles, he offers her a cat named Garbage that lived in his barn and is named because he eats garbage. When Angela declines Dwight's gift of Garbage, Dwight releases it into another part of the building. (Dunder Mifflin Infinity)
Andy gives Angela a gift later in the season when he is trying to convince her to date him in the form of a cat. Andy says that he found a cat wandering around the warehouse and caught it for her.("Money")
We can assume from when Dwight released Garbage and when Andy gave Angela Bandit, they are the same cat based on appearance and where Dwight left Garbage/Andy found Bandit.
When Dwight sets the office on fire, Angela gets Bandit and yells to Oscar, who is in the ceiling, to "Save Bandit!" Angela then throws the cat up into the ceiling, until it falls down on to the other side of the office. ("Stress Relief")
Pam explains that copiers go through "normal wear and tear", which includes, in a cutaway, Bandit chewing on the wires and being scolded by Angela.
Jim tries to prove that he can put a diaper on anything. He does so to Bandit, with Angela looking at him, angered.
When Angela and the Senator become separated, Angela, Phillip, and her many cats, including Bandit move into a small studio apartment (Paper Airplane).
Bandit is taken away by Animal Control after one of Angela's neighbors reported the number of cats she had which was more than the number of pets allowed in her studio apartment (Living the Dream).