| Type: | Bishop |
| Honorific Prefix: | The Right Reverend |
| Aeschillus Petraeus | |
| Bishop of Turku | |
| Church: | Church of Sweden |
| Diocese: | Turku |
| Appointed: | 20 October 1652 |
| Term: | 1652–1657 |
| Retired: | --> |
| Predecessor: | Isaacus Rothovius |
| Successor: | Johannes Terserus |
| Consecration: | 24 October 1652 |
| Birth Date: | 1593 |
| Birth Place: | Grums, Swedish Empire |
| Death Date: | 27 September 1657 |
| Death Place: | Turku, Swedish Empire (Present-day Finland) |
| Tomb: | --> |
| Nationality: | Swedish |
| Religion: | Lutheran |
| Parents: | Olavus Eskilli Petræus & Katarina |
| Spouse: | N.N. Andersdotter Petraeus Anna Henriksdotter Kock |
| Children: | 5 |
Æschillus (Eskil) Petræus (born 1593 in Grums, Sweden; died 27 September 1657 in Turku, now in Finland) was Bishop of Turku in 1652–1657.
Petræus was lecturer and Dean of the grammar school in Turku. He was also the first professor of theology at Turku Academy and Rector of the University. Petræus was from the Swedish-speaking part of Sweden, but well versed in the Finnish language. He, among other things, led a Bible Translation Committee and published the first grammar of the Finnish language, Linguae Finnicae brevis institutio in 1649.[1] On 20 October 1652 he was appointed Bishop of Turku and was consecrated on 24 October at the Storkyrkan in Stockholm.