Wilhelmus Egbertus Antonius Janssen (1 September 1905 – 4 May 1972), better known as Father Chrysanthus[a] OFMCap, was a Dutch priest and biology teacher.

[3] Chrysanthus began studying Dutch spiders in 1939 after being inspired by Fritz Lock's book Aus dem leben der Spinnen, published the same year.

[3] Chrysanthus travelled to natural history museums in Frankfurt, Genoa, London, and Paris to consult their collections.

[8] As Chrysanthus became known for his work on New Guinea spiders, museums were interested in providing him with specimens as they lacked specialists in this area.

[2] Researchers who consulted him to identify New Guinea spiders included the ethnobiologist Ralph Bulmer,[9] the biologist Yael Lubin [he],[10] and the zoologist Michael H.

[3] He cleared up the taxonomic confusion with the identities and synonymy of C. atropos, C. saxatilis, and C. terrestris;[16][17] this was published in a 1965 paper in Tijdschrift voor Entomologie.

[21] In 1955, Chrysanthus joined the editorial board of the journal Tijdschrift voor Entomologie — a position he would hold until 1971.

[3] In 1981, the Indian arachnologists B. K. Tikader and Animesh Bal named the species Neoscona chrysanthusi after him "in token of high regard which the present authors have for him.

"[29] G. H. Locket named the species Nasoona chrysanthusi "in affectionate memory of the late Father Chrysanthus and in admiration of his work on New Guinea spiders" in 1982.