Bankruptcies are court cases, but unlike other court cases, a regular bankruptcy case has no plaintiff and no defendant. A creditor or the bankruptcy debtor or trustee may file an adversary proceeding within the bankruptcy case, and that adversary proceeding will have a plaintiff and a defendant. Otherwise, the parties to a bankruptcy case are the debtor, his creditors and the bankruptcy trustee.
A person who files bankruptcy is the debtor. If you file a bankruptcy jointly with your spouse, you are both debtors, and other parties may refer to you as co-debtors or joint debtors. The word "debtor" means a person who owes a debt. The debtor is not a defendant, because the debtor files a bankruptcy case to obtain debt relief. In an ordinary bankruptcy case, no one legally accuses the debtor of doing any wrong; the debtor has nothing against which to defend, and so he is not a defendant.
Creditors are the entities or people to whom the debtor owes money. Creditors include credit card companies, mortgage lenders, vehicle loan lenders, doctors and hospitals, utility services and taxing authorities, such as the IRS or your state government. If you owe a person, a bank, a business or the government money, that person, bank, business or government is a creditor. Creditors are also not defendants. Although they may be unhappy that you filed bankruptcy and may be opposed to it, in an ordinary bankruptcy case, no one accuses creditors of wrongdoing, and they have nothing against which to defend.
A court-appointed trustee administers every consumer bankruptcy case under Chapter 7 or Chapter 13. Trustees may also appear in Chapter 11 cases. The trustee represents the government and administers your estate for the benefit of your creditors. The trustee is not on your side, but he is not a defendant; his purpose is to sell assets or collect money to repay your creditors.
In some bankruptcy cases, the debtor, the trustee or a creditor may have cause to file an adversary proceeding. An adversary proceeding is a lawsuit within the bankruptcy. The case has its own case number, which is attached to the bankruptcy case number, and your bankruptcy judge will preside over the case. If a party files an adversary proceeding, the party who files the proceeding is the plaintiff in that proceeding. The party against whom the plaintiff files the proceeding is the defendant. For example, if the trustee files an adversary proceeding to collect money from a creditor, the trustee is the plaintiff in that case and the creditor is the defendant. If a creditor files an adversary proceeding to prevent the debtor from discharging its debt, the creditor is the plaintiff and the debtor is the defendant. An adversary proceeding is a separate matter, however; in the original bankruptcy case, there are no plaintiffs and no defendants.