For Avon there are a few that come to mind.
1986, first year of the newly formed Lorain County Conference, Avon at Lorain Clearview in Week 10, both unbeaten with the winner getting the conference title and a playoff berth while the loser turns in the equipment. Avon led early, but Clearview came back to win in double OT.
1996, Avon goes unbeaten and makes the playoff for the first time. Lost the D5 state semi by a TD to Marion Pleasant, who went on to end Versailles long win streak in dominant fashion to win the state title.
2004, Avon loses star RB Bobby LaRosa on the last play of the last practice before facing Coldwater in the playoffs. On top of that, several starters got injured and suspended before the game, so Avon had to go in severely undermanned and got beat up by Ross Homan and his Cavaliers, who would’ve been favored anyway.
2008, Avon loses in the regional final to Big Walnut in the D3 playoffs. Aurora, who Avon had beaten at Aurora in Week 1, wins the state title.
2011, Avon loses to a stacked Trotwood-Madison team in the D2 state final. No shame in it it. Just that losing a state final is a bad feeling.
2016, Avon enters the D2 playoffs unbeaten and ranked #1 by the AP. 8th seeded Avon Lake, who Avon had beaten earlier in the season, stuns Avon in a first round playoff game at Avon.
2023, Avon has Hoban in check for most of the state semi despite not having starting QB Nolan Good for the game. Hoban eventually wears down Avon and wins a tight one to hand Avon its fifth straight playoff loss to the Hoban machine.