Guido Virgilio Alvarenga Morales (born 24 August 1970, in Asunción) is a retired football (soccer) player from Paraguay, who was nicknamed "El Mago". He played as an attacking midfielder during his career.
Alvarenga made his international début for the Paraguay national football team on 14 June 1995 in a friendly match against Argentina (2-1 loss). He obtained a total number of 25 international caps, scoring three goals for the national side and was a participant at the 1992 Summer Olympics and at the 2002 FIFA World Cup.