Lassar

Lucas Finch (properly known as Brother Lassar) was a Krillitane who took over Deffry Vale High School in order to crack the Skasis Paradigm which would make both he and his brothers "gods". He was a very sinister alien and liked eating children for his lunch. Eventually, his plan was foiled and Lucas Finch perished along with the other Krillitanes when K-9 blew up a can of Krillitane oil, destroying both the Krillitanes and the school. (DW: School Reunion)