At Luna'a wedding, the entire front row of seats was empty. When Harry asked why, she said

"They're for those who are here spiritually, I suppose. See, that one's for Sirius, and the one next to it is Lupin- they were friends, right?- and that one's for Mad-eye Moody, and then Tonks, and my mum, and your parents, and Fred, and Professor Snape, and Dumbledore, and a few of my family members who have passed." 

Original sad chappie by me.