Johann I. von Brandenburg was born circa 1213 to Albrecht II. von Brandenburg (c1150-1220) and Mechthild von Lausitz (c1185-1255) and died 4 April 1266 of unspecified causes. He married Sophie of Denmark (1217-1247) 1230 JL . He married Jutta von Sachsen (c1228-1287) 1255 JL .
Children
| Name | Birth | Death | Joined with |
| Johann II. von Brandenburg (1237-1281) | 1237 | 10 September 1281 | Hedwig zu Werle (1243-1287) |
| Otto IV. von Brandenburg (c1238-1308) | |||
| Konrad I. von Brandenburg (c1240-1304) | 1240 | 1304 Schwedt | Constance of Poznań (c1245-1281) |
| Helene von Brandenburg (c1241-1304) | |||
| Erich von Brandenburg (c1242-1295) | |||
| Hermann von Brandenburg (?-1291) | |||
| Name | Birth | Death | Joined with |
| Agnes von Brandenburg (1257-1304) | 1257 | 29 September 1304 | Eric V of Denmark (1249-1286) Gerhard II. von Holstein-Plön (1254-1312) |
| Heinrich I. von Brandenburg (1260-1318) | 1260 | 14 February 1318 | Agnes von Wittelsbach (c1272-1345) |
| Mechtild von Brandenburg (1257-1278) | 1257 | 1278 | Bogislaw IV. von Pommern (bef1252-1309) |
| Albrecht von Brandenburg (c1258-1290) | |||
Footnotes (including sources)
| ‡ General |
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