Millwall will retire their number 20 shirt in memory of goalkeeper Matija Sarkic who died in June, aged 26.
Sarkic joined the Lions from Wolves in August 2023 and made 33 appearances last season.
The club plan to honour the Montenegro international, who would have turned 27 today, prior to their Championship season opener against Watford on 10 August.
A mural painting of Sarkic is also being planned at the Den while a "Matija Sarkic Award" will launch in 2024-25, for fans to vote for their top save of the season.
Sarkic was born in Grimsby and began his career playing youth football for Belgian side Anderlecht before joining Aston Villa.
He signed for Wolves in 2020 and had loan spells across his career with clubs including Wigan, Shrewsbury Town, Birmingham City - where he made 23 appearances on loan during the 2021-22 season - and Stoke City before his move to Millwall.