For someone outside of Israel: Kiddushin 37a
For an Eved Kenaani to wear Phylacteries: Berachot 20a-b; Ketuvot 28a-b
For escorts of a Coffin and for those involved in post-burial consolation: Berachot 17b-18a
For a Metzora: Moed Katan 15a
For an ex-communicated person: Moed Katan 15a
For minors: Berachot 20a-b
When minors become obligated in Phylacteries: Succah 42a