There are multiple definitions - click on the translation that matches your context.
Massegläubiger means:
Substantiv
partial
noun
CAREFUL: We would advise against using this over-generalized translation here because "preferred creditors" are not necessarily creditors whose claims arise after and/or as a result of the insolvency proceedings themselves.
a creditor that must be paid first if a company goes into liquidation (=goes bankrupt)
Preferred creditors should receive a full payout before any other creditors are paid.