diff --git a/src/cryptography/x509/extensions.py b/src/cryptography/x509/extensions.py
index b7ea72c..c0705a3 100644
--- a/src/cryptography/x509/extensions.py
+++ b/src/cryptography/x509/extensions.py
@@ -174,13 +174,15 @@
                 "must both be present or both None"
             )
 
-        if authority_cert_issuer is not None and not all(
-            isinstance(x, GeneralName) for x in authority_cert_issuer
-        ):
-            raise TypeError(
-                "authority_cert_issuer must be a list of GeneralName "
-                "objects"
-            )
+        if authority_cert_issuer is not None:
+            authority_cert_issuer = list(authority_cert_issuer)
+            if not all(
+                isinstance(x, GeneralName) for x in authority_cert_issuer
+            ):
+                raise TypeError(
+                    "authority_cert_issuer must be a list of GeneralName "
+                    "objects"
+                )
 
         if authority_cert_serial_number is not None and not isinstance(
             authority_cert_serial_number, six.integer_types
@@ -273,6 +275,7 @@
     oid = ExtensionOID.AUTHORITY_INFORMATION_ACCESS
 
     def __init__(self, descriptions):
+        descriptions = list(descriptions)
         if not all(isinstance(x, AccessDescription) for x in descriptions):
             raise TypeError(
                 "Every item in the descriptions list must be an "
@@ -386,6 +389,7 @@
     oid = ExtensionOID.CRL_DISTRIBUTION_POINTS
 
     def __init__(self, distribution_points):
+        distribution_points = list(distribution_points)
         if not all(
             isinstance(x, DistributionPoint) for x in distribution_points
         ):
@@ -426,22 +430,22 @@
                 "least one must be None."
             )
 
-        if full_name and not all(
-            isinstance(x, GeneralName) for x in full_name
-        ):
-            raise TypeError(
-                "full_name must be a list of GeneralName objects"
-            )
+        if full_name:
+            full_name = list(full_name)
+            if not all(isinstance(x, GeneralName) for x in full_name):
+                raise TypeError(
+                    "full_name must be a list of GeneralName objects"
+                )
 
         if relative_name and not isinstance(relative_name, Name):
             raise TypeError("relative_name must be a Name")
 
-        if crl_issuer and not all(
-            isinstance(x, GeneralName) for x in crl_issuer
-        ):
-            raise TypeError(
-                "crl_issuer must be None or a list of general names"
-            )
+        if crl_issuer:
+            crl_issuer = list(crl_issuer)
+            if not all(isinstance(x, GeneralName) for x in crl_issuer):
+                raise TypeError(
+                    "crl_issuer must be None or a list of general names"
+                )
 
         if reasons and (not isinstance(reasons, frozenset) or not all(
             isinstance(x, ReasonFlags) for x in reasons
@@ -569,6 +573,7 @@
     oid = ExtensionOID.CERTIFICATE_POLICIES
 
     def __init__(self, policies):
+        policies = list(policies)
         if not all(isinstance(x, PolicyInformation) for x in policies):
             raise TypeError(
                 "Every item in the policies list must be a "
@@ -605,15 +610,17 @@
             raise TypeError("policy_identifier must be an ObjectIdentifier")
 
         self._policy_identifier = policy_identifier
-        if policy_qualifiers and not all(
-            isinstance(
-                x, (six.text_type, UserNotice)
-            ) for x in policy_qualifiers
-        ):
-            raise TypeError(
-                "policy_qualifiers must be a list of strings and/or UserNotice"
-                " objects or None"
-            )
+
+        if policy_qualifiers:
+            policy_qualifiers = list(policy_qualifiers)
+            if not all(
+                    isinstance(x, (six.text_type, UserNotice))
+                    for x in policy_qualifiers
+            ):
+                raise TypeError(
+                    "policy_qualifiers must be a list of strings and/or "
+                    "UserNotice objects or None"
+                )
 
         self._policy_qualifiers = policy_qualifiers
 
@@ -676,9 +683,8 @@
 class NoticeReference(object):
     def __init__(self, organization, notice_numbers):
         self._organization = organization
-        if not isinstance(notice_numbers, list) or not all(
-            isinstance(x, int) for x in notice_numbers
-        ):
+        notice_numbers = list(notice_numbers)
+        if not all(isinstance(x, int) for x in notice_numbers):
             raise TypeError(
                 "notice_numbers must be a list of integers"
             )
@@ -712,6 +718,7 @@
     oid = ExtensionOID.EXTENDED_KEY_USAGE
 
     def __init__(self, usages):
+        usages = list(usages)
         if not all(isinstance(x, ObjectIdentifier) for x in usages):
             raise TypeError(
                 "Every item in the usages list must be an ObjectIdentifier"
@@ -866,6 +873,7 @@
 
     def __init__(self, permitted_subtrees, excluded_subtrees):
         if permitted_subtrees is not None:
+            permitted_subtrees = list(permitted_subtrees)
             if not all(
                 isinstance(x, GeneralName) for x in permitted_subtrees
             ):
@@ -877,6 +885,7 @@
             self._validate_ip_name(permitted_subtrees)
 
         if excluded_subtrees is not None:
+            excluded_subtrees = list(excluded_subtrees)
             if not all(
                 isinstance(x, GeneralName) for x in excluded_subtrees
             ):
@@ -965,6 +974,7 @@
 
 class GeneralNames(object):
     def __init__(self, general_names):
+        general_names = list(general_names)
         if not all(isinstance(x, GeneralName) for x in general_names):
             raise TypeError(
                 "Every item in the general_names list must be an "
diff --git a/src/cryptography/x509/name.py b/src/cryptography/x509/name.py
index d62341d..7e55f6e 100644
--- a/src/cryptography/x509/name.py
+++ b/src/cryptography/x509/name.py
@@ -54,6 +54,10 @@
 
 class Name(object):
     def __init__(self, attributes):
+        attributes = list(attributes)
+        if not all(isinstance(x, NameAttribute) for x in attributes):
+            raise TypeError("attributes must be a list of NameAttribute")
+
         self._attributes = attributes
 
     def get_attributes_for_oid(self, oid):
diff --git a/tests/test_x509.py b/tests/test_x509.py
index b1d627c..47b81cb 100644
--- a/tests/test_x509.py
+++ b/tests/test_x509.py
@@ -3680,6 +3680,14 @@
         assert hash(name1) == hash(name2)
         assert hash(name1) != hash(name3)
 
+    def test_iter_input(self):
+        attrs = [
+                x509.NameAttribute(x509.ObjectIdentifier('2.999.1'), u'value1')
+        ]
+        name = x509.Name(iter(attrs))
+        assert list(name) == attrs
+        assert list(name) == attrs
+
     def test_repr(self):
         name = x509.Name([
             x509.NameAttribute(NameOID.COMMON_NAME, u'cryptography.io'),
@@ -3700,3 +3708,7 @@
                 "=<ObjectIdentifier(oid=2.5.4.10, name=organizationName)>, val"
                 "ue=u'PyCA')>])>"
             )
+
+    def test_not_nameattribute(self):
+        with pytest.raises(TypeError):
+            x509.Name(["not-a-NameAttribute"])
diff --git a/tests/test_x509_ext.py b/tests/test_x509_ext.py
index f3677d1..749e52f 100644
--- a/tests/test_x509_ext.py
+++ b/tests/test_x509_ext.py
@@ -268,6 +268,11 @@
         with pytest.raises(TypeError):
             x509.NoticeReference("org", None)
 
+    def test_iter_input(self):
+        numbers = [1, 3, 4]
+        nr = x509.NoticeReference(u"org", iter(numbers))
+        assert list(nr.notice_numbers) == numbers
+
     def test_repr(self):
         nr = x509.NoticeReference(u"org", [1, 3, 4])
 
@@ -357,6 +362,11 @@
         with pytest.raises(TypeError):
             x509.PolicyInformation(x509.ObjectIdentifier("1.2.3"), [1, 2])
 
+    def test_iter_input(self):
+        qual = [u"foo", u"bar"]
+        pi = x509.PolicyInformation(x509.ObjectIdentifier("1.2.3"), iter(qual))
+        assert list(pi.policy_qualifiers) == qual
+
     def test_repr(self):
         pq = [u"string", x509.UserNotice(None, u"hi")]
         pi = x509.PolicyInformation(x509.ObjectIdentifier("1.2.3"), pq)
@@ -414,6 +424,13 @@
         for policyinfo in cp:
             assert policyinfo == pi
 
+    def test_iter_input(self):
+        policies = [
+            x509.PolicyInformation(x509.ObjectIdentifier("1.2.3"), [u"string"])
+        ]
+        cp = x509.CertificatePolicies(iter(policies))
+        assert list(cp) == policies
+
     def test_repr(self):
         pq = [u"string"]
         pi = x509.PolicyInformation(x509.ObjectIdentifier("1.2.3"), pq)
@@ -859,6 +876,15 @@
         assert aki.authority_cert_issuer == [dns]
         assert aki.authority_cert_serial_number == 0
 
+    def test_iter_input(self):
+        dirnames = [
+            x509.DirectoryName(
+                x509.Name([x509.NameAttribute(NameOID.COMMON_NAME, u'myCN')])
+            )
+        ]
+        aki = x509.AuthorityKeyIdentifier(b"digest", iter(dirnames), 1234)
+        assert list(aki.authority_cert_issuer) == dirnames
+
     def test_repr(self):
         dirname = x509.DirectoryName(
             x509.Name([x509.NameAttribute(NameOID.COMMON_NAME, u'myCN')])
@@ -973,6 +999,14 @@
             ExtendedKeyUsageOID.CLIENT_AUTH
         ]
 
+    def test_iter_input(self):
+        usages = [
+            x509.ObjectIdentifier("1.3.6.1.5.5.7.3.1"),
+            x509.ObjectIdentifier("1.3.6.1.5.5.7.3.2"),
+        ]
+        aia = x509.ExtendedKeyUsage(iter(usages))
+        assert list(aia) == usages
+
     def test_repr(self):
         eku = x509.ExtendedKeyUsage([
             x509.ObjectIdentifier("1.3.6.1.5.5.7.3.1"),
@@ -1417,18 +1451,16 @@
 
     def test_repr(self):
         name = x509.Name([x509.NameAttribute(NameOID.COMMON_NAME, u'value1')])
-        gn = x509.DirectoryName(x509.Name([name]))
+        gn = x509.DirectoryName(name)
         if six.PY3:
             assert repr(gn) == (
-                "<DirectoryName(value=<Name([<Name([<NameAttribute(oid=<Object"
-                "Identifier(oid=2.5.4.3, name=commonName)>, value='value1')>])"
-                ">])>)>"
+                "<DirectoryName(value=<Name([<NameAttribute(oid=<ObjectIdentif"
+                "ier(oid=2.5.4.3, name=commonName)>, value='value1')>])>)>"
             )
         else:
             assert repr(gn) == (
-                "<DirectoryName(value=<Name([<Name([<NameAttribute(oid=<Object"
-                "Identifier(oid=2.5.4.3, name=commonName)>, value=u'value1')>]"
-                ")>])>)>"
+                "<DirectoryName(value=<Name([<NameAttribute(oid=<ObjectIdentif"
+                "ier(oid=2.5.4.3, name=commonName)>, value=u'value1')>])>)>"
             )
 
     def test_eq(self):
@@ -1438,8 +1470,8 @@
         name2 = x509.Name([
             x509.NameAttribute(x509.ObjectIdentifier('2.999.1'), u'value1')
         ])
-        gn = x509.DirectoryName(x509.Name([name]))
-        gn2 = x509.DirectoryName(x509.Name([name2]))
+        gn = x509.DirectoryName(name)
+        gn2 = x509.DirectoryName(name2)
         assert gn == gn2
 
     def test_ne(self):
@@ -1449,8 +1481,8 @@
         name2 = x509.Name([
             x509.NameAttribute(x509.ObjectIdentifier('2.999.2'), u'value2')
         ])
-        gn = x509.DirectoryName(x509.Name([name]))
-        gn2 = x509.DirectoryName(x509.Name([name2]))
+        gn = x509.DirectoryName(name)
+        gn2 = x509.DirectoryName(name2)
         assert gn != gn2
         assert gn != object()
 
@@ -1649,6 +1681,14 @@
             x509.DNSName(u"crypto.local"),
         ]
 
+    def test_iter_input(self):
+        names = [
+            x509.DNSName(u"cryptography.io"),
+            x509.DNSName(u"crypto.local"),
+        ]
+        gns = x509.GeneralNames(iter(names))
+        assert list(gns) == names
+
     def test_indexing(self):
         gn = x509.GeneralNames([
             x509.DNSName(u"cryptography.io"),
@@ -2371,6 +2411,16 @@
             )
         ]
 
+    def test_iter_input(self):
+        desc = [
+            x509.AccessDescription(
+                AuthorityInformationAccessOID.OCSP,
+                x509.UniformResourceIdentifier(u"http://ocsp.domain.com")
+            )
+        ]
+        aia = x509.AuthorityInformationAccess(iter(desc))
+        assert list(aia) == desc
+
     def test_repr(self):
         aia = x509.AuthorityInformationAccess([
             x509.AccessDescription(
@@ -2743,6 +2793,12 @@
         assert nc.permitted_subtrees is not None
         assert nc.excluded_subtrees is None
 
+    def test_iter_input(self):
+        subtrees = [x509.IPAddress(ipaddress.IPv4Network(u"192.168.0.0/24"))]
+        nc = x509.NameConstraints(iter(subtrees), iter(subtrees))
+        assert list(nc.permitted_subtrees) == subtrees
+        assert list(nc.excluded_subtrees) == subtrees
+
     def test_repr(self):
         permitted = [x509.DNSName(u"name.local"), x509.DNSName(u"name2.local")]
         nc = x509.NameConstraints(
@@ -3050,6 +3106,24 @@
         assert dp != dp2
         assert dp != object()
 
+    def test_iter_input(self):
+        name = [x509.UniformResourceIdentifier(u"http://crypt.og/crl")]
+        issuer = [
+            x509.DirectoryName(
+                x509.Name([
+                    x509.NameAttribute(NameOID.COMMON_NAME, u"Important CA")
+                ])
+            )
+        ]
+        dp = x509.DistributionPoint(
+            iter(name),
+            None,
+            frozenset([x509.ReasonFlags.ca_compromise]),
+            iter(issuer),
+        )
+        assert list(dp.full_name) == name
+        assert list(dp.crl_issuer) == issuer
+
     def test_repr(self):
         dp = x509.DistributionPoint(
             None,
@@ -3129,6 +3203,18 @@
             ),
         ]
 
+    def test_iter_input(self):
+        points = [
+            x509.DistributionPoint(
+                [x509.UniformResourceIdentifier(u"http://domain")],
+                None,
+                None,
+                None
+            ),
+        ]
+        cdp = x509.CRLDistributionPoints(iter(points))
+        assert list(cdp) == points
+
     def test_repr(self):
         cdp = x509.CRLDistributionPoints([
             x509.DistributionPoint(