While I consider my formative years to be the ones during secondary school, I have never truly had a remarkable teacher until I was in junior college (equivalent to 6th form college in the UK or AP in America).
He was my math teacher. He was an extremely normal person with almost nothing noteworthy. He was neither witty nor particularly impressive at teaching and yet he left an indelible mark on me because of two particular incidents that i would say another day. But it changed my life.