Enter these codes in your console (~ button). Some of them may require sv_cheats set to 1

Code	Effect
npc_create npc_citizen	A citizen
ent_create_portal_metal_sphere	Bouncy metal ball
host_timescale # (default=1)	Changes speed of game, 0.1 = 10% of original game speed, 2 = twice the original game speed
change_portalgun_linkage_id # (0, 1, 2, 3)	Changes the portal linkage ID for the portal gun held by the commanding player.
firstperson	Changes view to first person
thirdperson	Changes view to third person
ent_create_portal_weight_box	Create a Weighted Storage Cube
fire_rocket_projectile	Fires a rocket out of your face. (Bugged)
fire_energy_ball	Fires an energy ball out of your face.
impulse 101	Get all weapons (Half Life 2 weapons also)
give weapon_portalgun	Gives you the basic portal gun. Upgrade with upgrade_portalgun
god	Invincibility
sv_gravity # (600=normal)	Lets you change the gravity in the game
noclip	Lets you go through walls and fly around
sv_portal_placement_never_fail # (1 or 0)	Place portals anywhere
buddha	Player can take damage but won't die.
impulse 200	Puts gun away but stil able to shoot
npc_create npc_headcrab	Spawn (live) Headcrab
npc_create_aimed npc_rocket_turret	Spawn a rocket turret
npc_create npc_alyx	Spawn alyx
ch_createairboat	Spawn an airboat
npc_create npc_barnacle	Spawn Barnacle
npc_create npc_combine_s	Spawn Combine Soldier
npc_create npc_gman	Spawn Gman with suitcase and never dies
npc_create npc_metropolice	Spawn Metropoliceman
npc_create npc_fastzombie	Spawns a "Fastzombie" from Half-Life 2.
npc_create npc_portal_turret_floor	Spawns a standing turret
npc_create npc_poisonzombie	Spawns a zombie that tosses Poison Headcrabs from it's back.
npc_create npc_breen	The man breen
ent_fire npc_rocket_turret toggle	Toggle rocket turrets
ent_fire !picker skin 1	Turns a targeted storage cube into a companion cube
sv_cheats 1 (0=off/1=on)	Turns cheats on or off
notarget	Turrets won't shoot at you
upgrade_portalgun	Used without portal gun: Gives a portal gun. Used with a basic portal gun: Gives full portal gun.
npc_create npc_zombie	Zombie OMG (They attack citizens,turrets,and you)