Evander Holyfield -- War Over 'Father of the Year' Award

Evander Holyfield is in serious danger of losing his 1998 Father of the Year Award ... and it's all because he allegedly defaulted on a $600,000 loan to a famous business mogul.

The man suing Evander is Yank Barry -- the CEO of VitaPro Foods. He's also a musician who wrote the song "Christmas Time Again" for a 1977 Engelbert Humperdinck album.

According to the suit, Barry loaned Holyfield $621,133 back in 2013 ... which Evander promised to pay back by June 1st, 2014.

Barry claims Holyfield used several valuable items as collateral -- including various championship belts, the gloves form his 1996 fight with Mike Tyson, his 1984 Golden Gloves ring, various boxing robes ... and his 1998 Father of the Year Award.

Barry claims Holyfield never paid back the full amount of the loan -- so, he's entitled to the rest of the debt plus fees and other costs (which adds up to $471k) ... PLUS he wants to collect the collateral, which is currently being held by a 3rd party.

Meantime, here's that Engelbert song ... enjoy.