Knuxulie

Knuxulie is the het ship between Knuckles the Echidna and Julie-Su from the Sonic the Hedgehog fandom.

Pre-Super Genesis Wave
Knuckles and Julie-Su were echidnas from rival clans who fell in love. Both of them were members of the Chaotix and sometimes went on missions together. However, they were separated by Thrash the Devil, who sent most echidnas into an alternate realm.

It is likely that Knuckles and Julie-Su would have ended up together if it hadn't been for the Super Genesis Wave as a statue of Lara-Su is seen 200 years in the future.

Light Mobius
In this alternate future timeline, Knuckles and Julie-Su live together but are not married. They have one child, Lara-Su.

Fanon
This pairing is mostly shipped by fans of the Pre-Super Genesis Wave Archie Comics. It is among the popular pairings for Knuckles, though pairings involving Knuckles and a game character, mainly Knuxouge and Knuxikal, are more popular.

It is the most popular ship for Julie-Su. Some fans who dislike the ship but don't want to exclude Julie-Su ship her with other characters, but none of these ships are as popular as Knuxulie.

Some fans dislike the pairing due to it being incest, as they are 4th cousins 12 times removed (the large generation gap is due to Julie-Su's family coming from the Twilight Zone where 1 unit of time passed for every 4 units of time on Mobius). However, their relation is distant enough for the pairing to be considered acceptable.