Ibidem was a science fiction fanzine by P. Howard Lyons.
Ibidem was published in Toronto, Ontario, Canada during the 1950s. P. Howard Lyons was a member of "The Derelicts", a group of science fiction fans associated with the fanzine Canadian Fandom.
By issue three, according to a review in The Science Fiction World Vol 1 No. 3 of August 1956 (edited by Robert Bloch and Wilson Tucker), the editorship of Ibidem is credited to Howard Lyons and Pat Lyons. Pat Lyons is also known as the artist Pat Patterson, whose artwork can be seen in many of the fanzines of this period of the 1950s, including A Bas, Canadian Fandom and Inside and Science Fiction Advertiser.
Ibidem was distributed by the Canadian Amateur Fan Publishers. Six issues were published.
Ibidem was also the title of a fanzine by P. Howard Lyons that he began publishing at the same but that ran for much longer, having to do with stage magic.